1989 Chevy Cavalier Z24 2.8 liter. Repairs for this problem: Replaced idle air control,throttle position sensor, cleaned out throttle body and plenum with spray cleaner,added sea foam to gas to clean injectors. Question: this car sit up not running for about 3-4 yrs,it will idle perfect but on acceleration it stumbles and dies,

it smoke and smells like it is running rich. it seems to be doing this between 1000 and 1750 RPM's. it will smooth out somewhat if you feather the throttle and raise the rpms up but it still misses some. do you think it could have a bad coil pack or module breaking down under a load?

Answer: Even with fuel injector cleaner, you could still have an injector cutting out. The best way to check injectors on your vehicle is to ohm each one of them out. You'd have to remove the plenum to do this, and remove each connector from each injector. They should read around 11-12 ohms, and anything below that is bad. You may also want to check the ignition system, such as spark plug, plug wires, ignition coil and the ignition module itself. Spray a little water around the ignition to see if you can get a plug wire or coil to start arcing. If they are old or original, it's worth the money to replace them.

Crank sensors act up at times under load when the car is hot, so that is something to check also. One last thing that could be causing your problem is the EGR valve sticking. These are known to go bad on your particular vehicle and would act up in the rpm range you mentioned. A leaking fuel pressure regulator will cause a very rich condition- so that may be the smell and part of your problem as well. Not running for so long, the rubber inside the regulator may be split. Fuel would be filling the vacuum line, so pull it off for a quick check.