I have an '02 LS V8. Somtimes when I'm in park, the rpm's drop dramatically for about a second but then come back to normal, and then drop back down, and keeps going up and down. Sometimes it goes so low the lights dim and the car almost dies. What could be wrong?

I have an '02 LS V8. Somtimes when I'm in park, the rpm's drop dramatically for about a second but then come back to normal, and then drop back down, and keeps going up and down. Sometimes it goes so low the lights dim and the car almost dies. What could be wrong?

does it coincide with the AC coming on? or moving the steering wheel?

mine does it with the steering wheel sometimes what would cause that. my explorer did it too so i didnt think twice about it

this repsonse is normal when you put any load on the engine just as quik ls was eluding to.