Engine Performance problem
1992 Chevy Silverado V8 Four Wheel Drive Manual 205000 miles
I have a 92 chevy silverado when it idles the rpm is at 1000 and every few seconds it drops about 500 rpms. I have have replaced plugs, wires, ignition coil, distributor, spark control, tps sensor which made it worse, fuel injectors, o2 sensor, and idle air control valve. I am am at my witts end please help.
I would check that truck for a vacuum leak. Especially if it's worse when cold. Sometimes a vacuum leak will cause the iac to act erratic. First check all vacuum hoses and connections. Then check the intake gaskets. To do this you can either use intake air cleaner spray and spray the intake gaskets along each side and front and back and listen for rpm change. Or use torch gas along intake gaskets and listen for rpm change.