It was not the fuel filter.

Replaced it, and it is still driving bad, although it does idle much smoother now. The filter that was in it was full of water and rust.

Someone we know who is a mechanic says it is either the throttle position sensor or the MAP sensor. Does this sound possible? Nobody has suggested it here so far. Going to change out the sensors on this car with the other Mitsubishi we have for parts.

We do not have an AutoZone here. Only Advance Auto. Would they check the codes on it?

That crap in the filter had to be pumped out of the tank...don't forget about the tank, fuel pump and strainer still being culprits...

map/maf are sometimes combined in the same sensor as in some nissans.

Is that possible? The MAP measures manifold vacuum... I would think that pressure changes would screw with the MAF's accuracy. I could see an atmospheric pressure sensor maybe, but MAP?
Why would you even need both a MAF and MAP sensor? Yeah, some newer engines with drive-by-wire throttle will go WOT while cruising to reduce pumping losses... Under those conditions, a MAP sensor would be pretty much useless for measuring air flow. But otherwise, there are pretty much two methods for metering air flow - speed/density using a MAP sensor, and direct mass air flow measurement.

Exactly

MAP and throttle position sensors were both replaced along with a loose wire (found where it went) to no avail.

The tank will probably have to go down unless anyone else has another suggestion. I can already hear my dad *****ing about it :(

Has an ignition system problem been ruled out?

It is possible your timing belt skipped a tooth on the cam gears? If so, the engine would be running like crap

I second this question. Maybe the plugs are fouled out? I still think a simple test a mechanic with the tool to do it could yay or nay whether the converter is clogged?
You could pick one of these backpressure testers up yourself: https://www.tooloutfitters.net/exhaus...er-p31676.html

Seafoam again - did you run it thru the engine via a vacuum hose line like I remember it says on the bottle?

For a real good Seafoam procedure, see this:
https://www.turbobricks.com/forums/sh...ad.php?t=35053

The C.W.T. process is basically:
[EDIT: First warm up the engine]
Hook up a thin vacuum line to manifold (between throttle body and the head somewhere).
Learn what 3K rpms sounds like so you can run it at 3K using the throttle wheel on the intake.

Suck up a quart of (preferably distilled) water thru the vacuum line. Suck a few seconds, pull the hose out of water, suck a few more seconds, etc. Work the throttle wheel to keep engine from stalling when needed, try mainting 3K rpm. This actually does a lot of cleaning - turns to steam in the cylinder.

Now do the same with the bottle of Seafoam.

When done go out and drive it hard. Up to redline multiple times.

You might see big clouds of gray junk out the tailpipe during any step of the procedure.