I have a 1991 300sel Mercedes, when you come to a stop light it stalls, this happens few times a day for a week and then it’s ok for s couple of weeks and than it does it again, I’ve changed the fuel filter, fuel pump, did a tune-up, don’t know what else to look for, any ideas would be welcome.
Good chance that either you have a dirty throttle body, which normally causes teh gas pedal to stick a little when you first step on it, or some misguided mechanic has adjusted the throttle stop screw thinking that he was adjusting the idle for you.
The idle speed is controlled by your computer via the IAC (idle air control) motor. But for the computer to control the idle, it first has to know that you took your foot off the gas pedal. It gets this information from the TPS (throttle position sensor). If the throttle is prevented from closing all the way, due to dirt or mis adjusted throttle stop screw, then the computer thinks you still have your foot on the gas.
The throttle stop screw is there to prevent the throttle body from being damaged by the throttle when it is closed suddenly, that all it does.