So I've Searched and read most of the following threads about this problem, but in my case my misfire only comes at idle.

Scenario: The car is a EVOMS GT700 kit, when cold starting the car the RPM dips and then catches to normal idle, as the car gets warmer it idles normally but I can hear the misfire. I get the codes P0300 and P0304.

The Plugs in the car are the platinum NGK's installed by BBI less than 6 months ago with fewer than 6000 miles and I have changed the Coil packs on all 6 cylinders. While the car was at BBI they gave it a compression and leak down test with call passed as a healthy motor.

I am assuming I have a vacuum leak somewhere, I have a Durametric and the car does not misfire during driving conditions. I get a check engine light every 2-3 start ups after I clear the code.

Any suggestion on this would be greatly appreciated, I wouldn't normally post if I wasn't so stump! 6-Speed as a great amount of topics in the search function.

Thanks.