Honda Car Forum

I've never heard of this before so maybe somebody here has come across something similar:

'89 Acura Legend
When cool the engine will start up perfectly and run perfectly...with the engine light on. If I turn the car off and attempt to start it again before it has cooled off it will start and run just fine as long as I keep just enough gas going to keep it at idle or above. When started warm like this the engine light will NOT be on. The problem is that when started warm and no engine light if I let off the gas the car will slowly idle lower and lower until it chokes out. If by chance it has cooled off enough it will sometimes start up without the engine light on, idle down almost to the point of choking out and then the engine light comes on and everything is back to running like a top. So...there is something that makes that engine light come on that is absolutely essential to keeping the car running at idle when the engine is warm. Any ideas?