Cfiles0920

Ok, 968 motor...the car will start right up and run fine, first is generally fine...then into second, and about 2500-3000 rpm it starts to studder...its just a short studder like someone is tugging on the back of the car sharply and i can hear the motor hesitate. (the best way to describe it). Occasionally it will act like it is running on 3 cylinders, but just briefly. It will do that through all gears while under load. As soon as the accelerator is released, wont do it. If i run the car for about 10 mins, it will go away, only to come back slightly at a constant interstate rpm. I have changed the rotor/cap/plugs and wires and the problem wasn't solved. Plugs looked good when i pulled them. I have pulled over on the interstate and just let it sit, bumped the wires, and it ran fine for about 30 minutes. (don't know if that really solved anything) I figure it isn't a bent valve or anything because it doesn't do it all the time. Any suggestions??? I would love to solve this problem so i can move on to bigger and better projects.. thanks guys.