Unless it was at WOT
 

Unless the tranny was "Auto-Bombed" -- for example at highway speeds shifting to N, flooring it to redline, and shifting it back to D, then that may not have done it. Also, auto-trannies since the beginning of time have a limiter that prevents the transmission from shifting to 1st gear for example at 80 mph, even though you've shifted it down to "1". It will, shift into 1st once that safe speed is reached.

Side track: What drives me nuts is that new automatics don't have the selection of all the gears. It'll have like D, 4, and L. What about second gear -- one of the most important gears? Chryslers are the worst about this, you want 2nd at around 40 mph for engine braking, so you shift it to "L", then at about 25, the transmission lurches into 1st without warning...and besides you can't start out in 2nd gear in low-traction conditions. Soon, there'll be like D and nothing else. 95% of the public doesn't even know how or why those extra shifter settings are for. I randomly polled someone and they replied "That's like if you're in the mountains or something, right?" <sigh>

Compaq888 -- I think you're transmission was weak since it was a rental. The "final nail in the coffin" I was told by a transmission repair person is to change the transmission fluid on a high mileage tranny with problems. The old gunk is actually is holding the clutch packs together and whatnot. Maybe dumping some transmission conditioning fluid in there could help the problem. If you're stopped with the car in D, try holding the brake and give it some gas. If it shudders or revs easily, then you know that the clutch-packs are toast. Otherwise, a bad sensor that's not displaying a CEL could be at work here. Otherwise, what goes on inside an automatic transmission is a complete mystery to me.

RH77

Re: Unless it was at WOT
 

The tranny was put in N at freeway speeds and put back in D. I did the brake and gas thing and at 1000rpm the car starts to move.

I checked the transmission computer and it says everything is working fine.

Re: Unless it was at WOT
 

I don't think the N to D thing would've done much -- it sometimes hunts for the right gear, but unless considerable throttle was given, I doubt that was the cause. So what exactly is it doing? Will it not shift into a higher gear on the highway, or engage the torque-converter? (which is kind of a mini-shift or sliding sensation with about 500 rpms decrease). If it's just not shifting into a higher gear, you may have to do some further testing. This may require some very high-speed runs. Basically run the car to redline in D, on the gear that's not shifting -- if you hit the rev-limiter and it doesn't shift, it should figure out that there's a problem and give a check-engine code -- a word of caution, to get to redline in 3rd of 4th gear might require speeds upwards of 100+ mph -- so maybe take it to a track and do some quarter-miles.

The next idea I have is, have you spilled anything on your shift lever? My Integra had some cola spilled onto the lever and it got sticky. Basically one day, the lever was stuck between D4 and D3 and I didn't know it. When it does this the transmission sticks in 3rd gear, no matter what the speed. It wouldn't accelerate from a stop very easily, being in 3rd. I got a CEL, freaked out, and took it to the dealer. Basically they took apart the trim pieces around the shifter, cleaned the mechanism and made sure everything locked into place when selecting a gear (and gave me a sizable charge for the effort). You may want to do this first -- get in there and see if you're actually in the right notch, or if something is preventing you from lining it up properly. And be careful if you try the first option...

RH77

shifting
 

That should not bother the tranny shifting at high speed - the pump continues to operate and the engauging of the top speed clutch happens at high speed all the time if you floor it and accellerate. Neutral is just all the clutch bands released - there are no gears meshing in and out they mesh all the time. It would be a little hard on the top speed clutch if you dropped it in gear with the engine at idle going really fast but that is only a one time engaugement and should not distroy it unless it was pretty shot already. Filter check on the tranny and fuel pressure check in the tranny should tell the story - any wear comes out in the filter and oil. From what I hear they are easier to repair than manual transmissions.

Re: Unless it was at WOT
 

I didn't spill anything. I press the gas harder and it doesn't accelarate as fast. Sometimes it winds out, like revving more before shifting. Sometimes the shift is hard or too soft.

shifting
 

Always better to back off the gas a little when you want it to shift - remember there are hydralic clutches that have to release one planetary gear set and engauge another and the motor is still trying to spin faster when you heit the next gear. So if you have it floored let up about half on the pedal when you want it to shift and it should shift faster and smoother with less stress on the clutches. It's been a while since I pushed an automatic.

I don't push it. My cousin
 

I don't push it. My cousin messed it up. Yeah sometimes I do that method.

When cold...
 

When it's cold, my car shifts hard unless I lift the throttle when it's going to shift -- especially 3-4. Sometimes I can catch it, but they have a mind of their own and it's one heckuva jolt.

Anymore I do the lift-method almost all the time to get into a higher gear sooner. Anytime I drive the TL (most weekends), I use the manu-matic 100% of the time. You have to lift or the torque of telling it to shift when accelerating would certainly kill it over time.

RH77

Friction Reducing Oil and Other-Type Additives
 

I also use Amsoil products and have for years. I change my oil every 30,000 miles and my filters every 10,000. I love the stuff. I have also treated all of my vehicles with Xcel Plus engine treatment. From all of the research I have read and from my personal experience, this is the best friction reducer on the market. Quick example - Lost all of the oil in my crankcase and didn't know it. Drove my Mazda 626 for 600+ miles with no oil at all. Didn't hurt the car one bit!! This made me a believer in Xcel Plus.

no oil
 

Are you for real - you didn't notice an oil light on? Sounds like I need to look at Xcel Plus - are you going 30,000 miles between oil changes and changing the filter at 10k to keep it clean? I heard that if you get a bypass filter that filters down to .5 - 1 micron it slowly cleans the oil like new and you just add some fortifiers and run it for a long time. Sounds like a great way to reduce waste oil.