Quote Originally Posted by speedminded
You'd be suprised. An ex had a '98 Civic that was idling erratically hot & cold...I replaced the idle control valve/solenoid and it fixed the CEL and it then idled fine UNTIL it warmed up. You'd have to keep your left foot on the brake and right foot on gas to keep from stalling. No CEL's. It ended up being a partially clogged cat.

Normally if a cat is clogged you'd think whether it was hot of cold it would have the same effect. I don't think the material in them expands much to heat so I don't know how or why it was effecting it. Made no sense to me but with a new catalytic converter it still runs fine 2 years later and passes emmissions
hey anything can be the cause....I think its his brakes lol

But yes I have seen that too...But going by how he said its running great at above idle I don't think thats his problem..Sounds more like tune up issue...But who knows could be his brakes