I have recently developed a high idle. It only does this sometimes. It will idle around 1500, after driving so the engine has reached normal operating temps. Another thing is that it will dip down then go back up, and continues. Does anyone have a clue. Maybe a sensor with the throttle?

 

i would check for a vac. leak, loose hose or cracked

 

Well i couldnt find any vac. leaks so i thought of the high idle control valve. I noticed when it would fluctuate, the idle would go to where it is at warm up. I had it bypassed, so i cleaned it with Deep Creap, and then unbypassed it so it is now heated. Hopefully this works.