Join Date: Jun 2017
Location: Kansas City, Mo
I have to chime in because this sounds like a similar issue I have, but on a completely different situation.
My car is an '06, stock N/A engine (obviously, like I said, a very different situation). I ordered new spark plugs from a well known vendor. I meant to order NGK BKR6EIX, but was sent NGK BKR7EIX. 6's being for N/A cars, 7's being for supercharged cars. After inquiring, the vendor indicated that the 7's will be perfectly safe to use on my N/A car so I proceeded with the install. They work fine once they are heated up. When they are cold, however, they act exactly as the OP describes. Understood that S/C cars have a lot of other potential complications to cause this problem, and perhaps its just coincidence that my situation and the OP's situation are similar, but thought I'd add my experience to the equation since the spark plugs have not yet been discussed as a potential cause for the OP's car.