alwayswright328

I have a 92 Mustang. I just rebuilt the motor and put it in this past Sunday. I have GT40P heads which I had surfaced, magnafluxed, and had a valve job done. The crank was turned and polished and the block was ball honed. I had this same problem before the rebuild which is what concerns me. when I start it after it has set overnight or even a few hours, it will idle fine but when i try to drive it gets really sluggish and begins to pop while I'm attempting to accelerate. I feel the pop in the gas pedal and after it pops for a couple seconds it runs normally. As of now I haven't taken it above 2,000 RPM's because I'm still breaking it in, but prior to the rebuild it would do something similar around 4,000 RPM's when under a load. It could rev there but if I was really on it, it would sputter and lose all power. The fuel pressure regulator is an aftermarket BBK and has never had a vacuum connected to it which was not a problem in the past. The spark plugs, wires, Rotor and Cap are all brand new. I would appreciate any input!!! Thanks