I have an 89 Rs with a brand new GM 2.8 V6 put in 7000 miles ago, sometime the service engine light is on and when it is the car idles rough and stalls when I come to a stop, But sometimes I start my car and the lights not on and the car runs and idles normal, I've changed the MAF, Throttle Position Sensor, O2 sensor. All with no luck, any help would be very appreciated

 

I would say first, do an engine code check. Then give us the number(s) you get.

Im just going to thru a random guess out tho, have you checked the timing?

 

Timing is correct I'll try and get the code from the service light