Chevroleete caviler - car wants to stall or does stall when idling after warmed up - not always. When in drive at idle speeds once in a while cars revs will jump up to 2.5 - then have to restart

Check coolant temp sensor. These fail often and cause all kinds of mystery problems. This unit acts much like a choke on old carb engines and can fail in different ways. Most common (I think) they fail such that the ECU thinks the engine is cold when it has begun to warm and thus the ECU delivers too long a pulse to the injectors so that the engine runs way too rich. I think it is also possible for the sensor to fail at any point between cold and warm such that the fuel mix is wrong except for the particular temp at which the sensor is stuck. Also O2 sensor has some fuel "trim" input.

will be a sensor problem need to get the OBD read by a suitable mechanic

Should be on or near the fuel injector supply rail.

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve but always run a OBD2 fault code as well as the cleaning procedure. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control

Engine stalls or RPM fluctuates at idle up and down or dies near idle.

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve but always run a OBD2 fault code as well as the cleaning procedure. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve but always run a OBD2 (1996 and newer) or a OBD1 (1995 and older) fault code as well as the cleaning procedure. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control

I would check for an intake leak somewhere. Cracked or broken vacuum lines will usually be the problem. Good luck

Here is the common cause of surges, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Here is the most common cause of surges and stalls at stops and low idle speed and rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Believe it or not you just said the solution to your own problem manufacturers specs requires for any adjustments to engine idle or other carburator adjustments to be preformed while the engine is idling and at normal operating temp in plain english let the car warm up then make your idle and mixture adjustments if this doesnt solve it i would check the auto choke and make sure it is opening at normal operating temp hope this helps good luck