Stalls at any speed

95 Buick Century 3.1 L engine stalls while driving at any speed on any type road. Seems to be much worse during hot weather. Seems to happen just as I let up on the accelerator. Getting progressively worse. Mechanics can’t diagnose this intermittent problem. No fault code on the OBD 1. Car starts OK after it stalls although it’s becoming more difficult the longer this problem persists. Mechanics say wait until you have a failure and a fault code will highlight the problem. Meanwhile I’m a highway risk and cause traffic jams when the car stalls. Need help!

The problem might be with the Idle Air Control valve. These can be effected by heat where they become lazy and they fail to go the proper position for the idle condition.

If this isn’t functioning properly, and if you lift your foot completely off the accelerator while driving, the IAC valve doesn’t react to allow air into the engine when the throttle plate closes in the throttle body. No air into the engine = engine stalls.

If this is the problem, the OBDI engine maneagement system won’t let you know. As the IAC position isn’t monitored with OBDI


You may have to “play” the gas to get the engine started, yes?
Clean the throttle blade and throttle bore, idle air control valve (iacv) air passages, iacv pintle with Throttle Body Cleaner.
Check the engine coolant temperature sensor (ects) with a multimeter. At different temperature, the ects resistance will be different. If those ohms values are wrong for the temperature, the engine can be too rich, or too lean, which can cause driveability problems. Any normally astute mechanic can do these checks.