94 cavalier Idle problems

My 94 Z24 3.1 liter cavalier is not idling right. When you start it cold it idles about right but when you drive it for about 30 minutes the idle drops so low that if you keep driving it when you stop at a stop sign or behind someone it will quit. It will idle 600 rpm or less. If you keep your foot on the gas and idle it up it will keep running but if you take your foot off the gas it will quit. I checked the trouble codes and a while back it give me a fuel air mixture code ( i think code 35 ). I changed it and it did not help. I rechecked the codes and it showed none. To day when i drove it and got it warmed up it flashed a code for a second and went out. Checked the codes while the engine was hot it give a map sensor code 34 and code 35. I changed the map sensor and now the only code it gives is code 33 which is map sensor again. Any ideas this thing is driving me nuts. And I'm a bad back yard mechanic so try to simplifie it. Thanks:runaround:

Fiserman

My 94 Z24 3.1 liter cavalier is not idling right. When you start it cold it idles about right but when you drive it for about 30 minutes the idle drops so low that if you keep driving it when you stop at a stop sign or behind someone it will quit. It will idle 600 rpm or less. If you keep your foot on the gas and idle it up it will keep running but if you take your foot off the gas it will quit. I checked the trouble codes and a while back it give me a fuel air mixture code ( i think code 35 ). I changed it and it did not help. I rechecked the codes and it showed none. To day when i drove it and got it warmed up it flashed a code for a second and went out. Checked the codes while the engine was hot it give a map sensor code 34 and code 35. I changed the map sensor and now the only code it gives is code 33 which is map sensor again. Any ideas this thing is driving me nuts. And I'm a bad back yard mechanic so try to simplifie it. Thanks:runaround:

Fiserman

It could be a dirty throttle plate or a dirty idle air control valve. Get some throttle body air intake spray cleaner. Remove the air filter housing and ductwork out of the way on the throttle body to expose the plate(s) inside. Spray all inside and let the grime and dirt run out, then wipe it out. If it's equipped with an air control valve on the body, unscrew the assembly to expose the valve and repeat the process with that. Let it dry for about 30 min before starting the engine. This worked for me, hope you have the same luck!