Another possibility would be the cat getting blocked in the exhaust - which happened to me with my old (Rover) Metro!. It was like a rev limiter / speed limiter - but, if you changed up a gear e.g. 3rd to 4th, you could go a bit faster - presumably as the engine gave more power for the same amount of exhaust gases!.

When you rev the car, does it give a good flow from the exhaust (s?).

If it is the fuel filter / something like that, then it won't necessarily give problems at the same RPM all the time. If you rev it in neutral when it is stopped, can you go higher than 4000-5000rpm?.

Would running fuel injector cleaner through a couple of tanks of gas clear it up without removing the fuel tank?

I don't know if unstable bob has worked on Mitsu Galant's. I've changed a couple in-tank fuel pumps and their filter screens on our cars (not Mitsu though) and it did not require tank removal. Still a PITA, you access the tank's innards via an o-ring'd hole at top of tank, via the trunk or hatch.

The main fuel filter is a separate item, would be somewhere in the fuel line but I'd expect it to be outside the tank, probably under the car. In the good old days they were in the engine compartment but that was for low pressure systems with carburetors.

Definitely worth a shot. Supposedly Techron is best, or at least one of the best. Then there's Seafoam, which cleans everything in the fuel path including the valves. I'd use Techron first; Seafoam kicks up a lot of carbon and junk and blows it out the exhaust.

I went ahead and got Seafoam. I didn't see techron anywhere, and I figured that it needed the most powerful stuff out there, considering how bad it is.

Put some in, let it idle for 5 minutes or so, then I drove it and pushed it hard. It was still doing it though. The car would lurch a little bit, but it would eventually go on to a higher RPM, though it definetly fought to do so. I brought it home, let it idle for another 10 - 15 minutes, then drove it again... and it was worse than ever. I couldn't even get it over 3,000 RPMs this time. The oil light also flickered on and off when it idled. I could only assume that the cleaner was causing this.

I can only hope it will be better with a little more driving. It was definetly kicking out a lot of carbon which is good. I head out to college soon and I'd like to have the car running nice before then. If there is anything I can do without having to involve my dad (nightmare) then I'm all for it.

Does anyone know where I could possibly get a schematic of where the fuel filter and pump are without having to buy a repair manual?

I would also simply do a tune up on the car, replace those parts that are recomended every few years, you might also have a compression test done to make sure that the head work that was done fixed all the valves, as valve float could do simaler things, as the valves wouldn't close all the way, and that could come up because of compressed valve springs.

but really, do a tune up first.

Never did a fuel pump on a Galant. And it seems like every thing I've ever worked on required dropping the tank. Although I will admit to breaking out the wiz wheel and creating an access panel on a few late model Camaros and Firebirds, since those cars also require dropping the rear end to get the fuel tank out. ;)

Well, I would say it is a given that the fuel pump is located in the fuel tank, and hopefully it is self explanatory as to where the tank is, and what it looks like. The pump fits into the tank through an opening in the top of the tank, and you have to figure out if the pump is accessible through the trunk or hatch as Bruce suggested, or if the tank has to come down. As far as the fuel filter goes, just head down to the local parts house and pick up a new filter, then follow the fuel line out of the tank until you find the item that matches up w/ the filter you just bought. Not sure how Mitsu secures their filters in the line, though. Sometimes there are threaded fittings, sometimes there are pressed in connectors, sometimes a combo of both, or might be sumthin' I've never even heard of! :eek:

if your car has a MAF it could give the same lag when you acell if its bad. it feels like its running out of fuel the higher your rpm is and some cars stall out just as you press the gas.

I picked up a fuel filter today. Hopefully can get it installed tomorrow. Someone else I talked to said it could be the throttle body (idk what that is). Hopefully this will clear it up.