Quick history--I did a timing belt/water pump replacement on the car. Drove fine for a few days, then started making noise. Tensioner nut had gotten loose and disappeared, I guess I forgot to tighten it all the way down. So I got a new nut and a new belt (as the timing belt had lost about 1/8" of it's width and there were fibers all inside the cover), and got it all back together. Now it idles at about 1800-2000, and surges after you blip the throttle at all. If you run the a/c, the idle is about normal, and once you turn it off, it starts surging.

This is an immediate post after doing the job, I have not left the driveway yet. Search results only mentioned coolant level, which I didn't even touch, and IAC, which was fine before I put the newest belt on. I don't believe it's the IAC, I only disconnected two hoses which I reconnected, and I don't know what else to check. Is there a possibility I have something too tight/loose? Any help would be appreciated.

Thanks guys.

 

I would check your MAP sensor and once more bleed the coolant system in case there is some small bubble that is causing the problem. I'm guessing you don't have a check engine light cause the next thing I would be thinking is the CKP was damaged, but you would be getting codes. Did you unplug the IACV by any chance and see if the surging went away? Hopefully you find it and its something minor like a unplugged sensor. Good luck