idle surge

[Nixon1]

That's EXACTLY what mine does. Cold idle is fine cause it's high, but when it's warmed up it'll surge. Like I said, at least yours doesn't get to the stalling phase. What I find will sometimes calm my engine down and keep it from surging is lightly tipping in on the gas until the rpms are at the top of what it's surging to...so if it's surging to around 900, say hold it at 1000 for 5 seconds or so, then SLOWLY release the pedal until you're off of it. That works for me sometimes--sets the car back into a normal idle pattern. If that doesn't work, killing the ignition and restarting it usually solves it for me too if it's a bad surge.