First start up of the day is fine. After its been driven, sometimes it wont start unless I pump the gas pedal while turning the key. Car runs fine, but sometimes while stopped at a red light it stumbles like it wants to turn off and sometimes it does. When it occurs too much, I spray the throtle body intake and it seems to do the trick but only for a few days. I've changed fuel & air filters, spark plugs & wires, O2 sensor, cleaned fuel injectors, egr & pvc valve. Fuel pump makes its electrical hizzing sound when key is turned so i take it its working fine. I havent learned how to check for vaccuum leaks. Repair shops dont mention the minor possibilities, they right away suggest the most expensive repair, fuel pump.
Why does car only start if gas pedal is depressed & occasionally stalls at idle? on 1997 Chevrolet Lumina