Cold starting problem

[Phil The Rep]

I blew the head gasket recently,on my S2. I've had the heads skimmed and refitted, but now when Starting the car it fires up straight away on a fast idel for about a minute, then slows to normal idel. But when I try to pull away the engine misfires alot untill its warmed up. I've replaced the cold start sensor and the throtle position sensor but the problem is still there. Any ideas to solve the fault?

[F908 Tim]

How does it run when it gets up to temperature?
Does it smell normal when cold started?
What are the plugs like...any clues here?

[Phil The Rep]

The engine runs fine when its warmed up and restarting is no problem. On tick over the exhaust does make your eyes sting abit.