Hi all. I'll cut right to the chase with symptoms and then what repairs I've completed thus far.

Symptoms:
Trouble Codes 21, 22, 34 & 44
Rough Idle - Surges
After a while of idling, the rpms kick way up. (Around 1200 I'd guess)
Dies when coming to a stop unless I put it in neutral
*new* Blue Smoke from exhaust


Repairs:
New TPS, ICM, coil pack, Intake Air Sensor, MAF, plugs, wires, oil filter, removed fuel rail and cleaned injectors, ignition switch, fuel filter, fuel tank, sending unit & pump, water pump, thermostat (OEM), 2nd thermostat (180⁰), PCV

The vehicle was sitting, garaged for 13 years before I received it. I replaced the tank, sending unit, pump and filter, gave it a tune up and it ran like a champ for a couple months. Then started idling rough, had no power, would die randomly and stalling after it warmed up, but ran fine cold. Changed plugs wires, air intake sensor and coil pack. Seemed to fix it for a couple weeks. Problems came back with a vengeance. It would crank and start to fire but die when I let off the key. Started fouling plugs left and right. Changed the ignition module, maf, throttle position sensor, PCV, 02, ignition switch, plugs and MAF housing. Finally got it started. Hard to start and Idled a little rough, drove it two days. Died on my wa home from work. Let it sit a couple days, now it will fire right up and idle rough (surging and seemingly missing) finally started giving me codes. 21, 22, 34 & 44

21 and 22 are saying both high and low voltage from TPS, 34 is lean exhaust (probably from the 21/22 scenario) and 44 is saying low voltage from 02.

Any insight is appreciated. Unfortunately this is my only car and at this point I've dumped so much money into it, I've gotta get it running.

Thanis very much

-Rev

108k miles, 3.8ltr, automatic trans.

I havent logged in for 4 years but i am here now. I have a 1990.. i think you need a computer.
I took the ECM out of a 88 lesabre, put my PROM chip in it, and it fixed a slew of engine running and electrical issues.
You have replaced far too many parts guessing.
100 bucks with a core at an auto store and a day wait. see if they accept electrical returns. if they do, try another computer. it takes 10 min start to finish to plug in new computer and you dont need to remount it or put the carpet back etc. Just some basic hand tools. Hell, even clean the ECM with contact cleaner on the connector and make sure free of corrosion. any water damage or sunroof on the car?

If i didnt need the ECM i would give you mine
Remember, you HAVE to use your PROM chip. Its inside a little cover on the ecm

You know, I would have said there was no water damage, but now that I really think about it, all of this started after i decreased the engine and started getting it washed regularly.

Maybe I blew some water in somewhere it shouldn't have been.

I'll try cleaning the connection first, if it doesnt work, a new ECM, it is.

*degreased

Hmmmmm . . . I see a lot of parts . . .

. . . but no diagnosis. One part I don't see: Idle Air Control valve. I'd lay odds on this based on your description.

I haven't cross-checked your code definitions. Low TPS voltage would not lead to lean exhaust by itself, and low voltage from O2 means the [lean exhaust] read is probably inaccurate anyways.

I cleaned the IAC and it seemed to be in functioning order. I just got a new ECM. Trying it now. With report back with findings.

Could be, but PCMs don't usually go bad then come back to life and work well again.

Ouch, my experience has been: Don't batch wash these older engines (like spray all clean all etc. especially with pressure). Water gets into everything.

Good luck!