I have A 1998 chevy Blazer with a sporadic idle under 900 RPMs to stall, runs well over 1000 RPMs but when you release feeder goes to rough idle and stalls sometimes. Replace map sensor, tps, speed sensor, transmission neutral switch, mass air flow twice,, fuel pressure OK , Still runs the same, ANY IDEAS ?

 

Check all your vacuum lines

 

My vaccum actuator for the 4 wheel drive is defective, could that cause a problem with the sensors if the actuator has a leak?

 

Yes, plug the hose to it and see if the roughness goes away.