Idle Surge on cold start

[Tal92on]

Oke soooo.... for a while now my car (92 awd talon) has had a weird idle surge at cold starts, but once the car warms up it sits at a steady 800rpm idle. When started at cold, it fluctuates from around 1100-1600 pretty rapidly. I've tried a different ISC, even a whole different throttle body, a different ECU, and it has a new coolant temp sensor in it. I'm a little thrown off by this.... i have read plenty of forums about idle surge and i've heard people say an oxygen sensor could cause this but that doesn't even really make sense because its idle surging at open loop. Think it could be something with the Fast Idle air Valve? Idunno, if anyone has any ideas or input it would greatly be appreciated, Thanks- Sean

[Blackcrow64]

Vacuum leak? That would be something that could cause it to surge like that while running in open loop.

Does it run not quite as good as it should once it stops surging? This too would point to the possibility of a vacuum leak causing the problem...

Trying to think of any other sensors that could be causing this in open loop...

[Tal92on]

It seems to run just fine after it warms up and the surging goes away, but ill check around and look for leaks with some propane. Thanks