Car stumbles when cold and progressively gets better the warmer it gets

[Evil94Evo]

This car is frustrating. When the motor is cold it will only rev out to roughly 1500 rpm. As it warms up it starts to rev higher until its fully warm and then will hit redline (if you wanted to). Would a bad o2 sensor do this since they are heated, my theory is that if the heater part wasn't working this might be possible. Any other ideas? We have tried a lot of spare parts on this car.

Thanks.

 

[dented_coffee]

My 1993 eclipse gs was doing that. I changed the ISC and it stopped. A cold start would bring it to 12 or so but on for a few seconds to initially warm it up.

Test your ISC make shure its not going bad.

test them in this order or sequences.
1 2 3
4 5 6

1&2
2&3
4&5
5&6

They should all be 28-33ohms if anything is under or over that margering then it should be replaced.

 

[eeeewidner]

+1 on the iac. I have seen one short out and also causing the ecu to catch fire as an added bonus. Get the car warm and unplug it for testing purposes.... Then shut the car off and restart it to see if the problem comes back.....If it doesn't then the iac is shot....