I have a 2005 3 s with a 5-speed on it and recently (last 500 miles) the car has begun to idle very rough. I changed out the spark plugs, checked all my electrical connections, and run the highest octane fuel I can get (93). I have a SRI on it but it idled bad before and after that was on so what else could be the problem? It doesn't hesitate or lose any power while going but it vibrates the whole car at idle even in neutral with the clutch out.

 

It sounds like your rpm is low

 

it does idle around 750rpm but i can't think of anyway to make it idle higher.

 

How's your gas milage? Could it be the 02 sensor? Did you reset the ECU after the intake install?

 

actually my gas mileage isn't that great but no CEL and I've reset the ECU a few times since the install.