i have an 87 na and it idles like at 1500 after its warm and just bounces around a little in that area. i have check the bac valve its clicking. i disconnected the bac and tried to use the idle speed screw and nothing. i even used the fuel air screw the one on the varialbe resistor and that did not do anything at all full trun either way. i have check timing but it was at the way its idling now so its close but bounces around a little also. oh and just to throw this in there i cant see any coolant leaks and i just put a whole jug in and it still says to add more coolant b/c my warning light comes on. it goes off when i top it off then comes back on after running for a litttle bit. and it seems to be overheating i have not let it overheat but i can hear the coolant boil and hiss from the overflow tank.

 

Sounds like your fast idle thermowax or cam is sticking.

 

cool ill get the fsm and run through that and get back at u