i just put the heads on my car and everything's running ok. for some reason though, when i turn on the car, she stumbles for maybe 20 seconds at first and you can hear a loud hissing noise comming from the IAC. then it goes away and the car sounds fine. second.. and this is the most important one. when im going WOT through the gears, the car feels strong, then hessitates, then gets strong again.... it feels like it's surging at points, then going back to normal. what could this mean? thanks for the help guys