hello. i have a 1988 rx7 gxl n/a..i have a video posted on youtube with my problem (http://www.youtube.com/watch?v=fv7lGHq2C9Y) it starts up beautifully. if its cold it revvs up till its warm.. if not then it just idles around 1500rpm.. but it dips down a notch. comes back up...dips down.. and back up to 1500 and repeats... i found out today that if the headlights are on it idles just fine....weirddd

 

Check to make sure cable isnt bound, check throttle stop screw and biss, see if cold idle thermowax is actally disengaging once warm, most importantly check for vacuum leaks(most likely situation).

 

wouldn't this be the BAC kicking on and off? like if he properly sets his idle where it should be, and he has no vac leaks or anything, then it should stop doing this?

 

Vac leak makes engine idle up. Ecu sees 1volt on the tps(idle position) so it does the decel fuel cut till the engine is around idle speed then stops, vac leak allows engine speed to pick back up and repeat. The ecu will also do this when the TPS is not properly set or is malfunctioning.