Runs rough when starting warm.

[Beemerdan]

I have a 91 318i with the stock M42. It starts fine when cold, but when I start it after the engine warms up, it idles super rough and doesn't have much power. Once I gun, it and get it and get it up to speed it works fine and continues to be fine.
Any ideas what this may be?
Thanks!

[salvuhdor]

You didn't elaborate too much on the problem but this would have me thinking that the exhaust system may be shot. I'm saying this because I've had an m42 with a shot catalytic converter and had this problem.

Though this problem is not common. What is common is vacuum system failer.

Please elaborate on the problem, when was last tune up? any known problems to the car? when you gun it will the problem reappear?

how many miles on the car?