My 86 NA idles smoothly and above 3000 it runs smoothly but between 1200 and 3000 the speed fluctuates constantly. If I raise the engine speed up to say 2000 rpm, It wont stay at that speed. It will drop off by several hundred and then raise back up to 2000 again and again. If I raise the engine speed above 3000 rpm, the speed can be maintained easily.

Anybody heard of this before. I did a search but I only came up with poor idle conditions.


ash

 

sounds like your throttle position sensor, is either out of adjustment, or worn out.