Stalling/Missing

92 Lumina with 3.1 155K miles. Engine dies at startup or idles rough and smells rich. Sometimes need to keep accelerator pressed to idle up to continue running. Hot or cold engine seems to make no difference. Approaching stoplight, let foot off accelerator and many times engine dies. Misses when accelerating at highway speeds and sometimes engine dies at highway speeds. Slip it into neutrol and it restarts ok. Problem is worse with AC running. I have replaced plugs, wires, oxygen sensor, throttle position sensor. I swapped computer but problem still existed so I put old one back on. I need help guys, I am wearing out my starter. Local repair shops have not been able to pinpoint the problem and I hate to take it to a dealer and give them hardearned megabucks!! Check engine light does not come on but it does work.

not sure if this will help but mine had the same kinda problems, kept stalling when driving...

what i had to do is re-teach my car how to idle...

ok reset ecm by pulling fuse underhood (20 seconds)
A/C radio everything OFF
start engine without touching accelerator ... (keep trying if stalls)
once started place in drive with foot on brake
sit here for 7 minutes
place in park and switch off engine, wait 10 seconds
start engine, place in drive and wait another 7 minutes
switch off engine...

car has re-learnt how to idle if ecm is fine.

also clean out your throttle body, and check spark and fuel try running a fuel system cleaner through it also...

That ecm reset trick works, was having similar problems with a 93 3.1 euro sport but the veh now runs fine