engine miss SS

Have any of the Redline owners had this issue?

08 HHR SS
long story short dealer put new injectors in and still has issue with a miss fire on Cylinder #3, P0303. Now the GM Techline is saying a valve must be hanging on #3 causing a the missfire. This only occurs at start up after it has sat for 8 to 12 hours in sub 30 deg weather, but at start up the temp has been anywhere from 15 to 35 deg. So any how I find it really hard to believe that a sticky valve is causing an issue only at start up. no issues any other time. I am just a little nervious for the dealer to put a new head on this. I am concerned I will now have more issues with the items they have to remove to get to it for instance intake leaks, Turbo issues...... Has anyone else had or heard of this? thanks

I think it might be a bit more descriptive, is not a real miss-fire, is a drop in RPM at low idle. Almost like the falling of a cylinder at rest, MAF would make sense, I'll do with it. Its Gonna be a few months before he can recover financially from the purchase , so the performance parts will have to wait a while.

to followup on this. the dealer put a new long block in back in April and at this point 6k miles later I have not had any issues. with exception of the manual trans hard shifting after they were done with the repair. my exact concern in the first place. The true test for the motor will come whne the temp starts dropping the end of October.