Need help with 1991 Lumina

My Lumina will run great when giving it pleanty of gas, as you let up it trys to stall but doesn't unless you are at a stop. It starts right back up and jerks like crazy til you put foot hard on gas. Have checked all vacumes, replaced crank sensor, ignition module, plugs and wires. Any sugestions?

UPDATE: I found the problem. When my brother replaced the ignition module he didn't clean the corosion off of the plate it sits on. Got that cleaned up and it is running great now. Thanks for the tips.

Check Idle Air Control and EGR for sticking...

I had a problem just like that in my 93 Lumina. The problem i had was that my Lock up soloniod in my transmission was shot. It was making the car buck when trying to stop, then you would get the car to stop and it would just stall. Then it would start and run good right after that! But really i dunno...Im just a NOOB!