[Rwillia4]

Glad to hear the engine is running. When I installed my motor I had the same problems. I think this was do to the engine builder tuning to his test facility for the highest HP and not to items that are car dependent such as, headers and exhaust. I agree that your ECU should have been sent with the motor.
The effect on my motor was very rich conditions, to the point that it would spit flames out of the exhaust when backing off the gas. It ended up blowing a head gasket (coughed the gasket out between two cylinders). After getting that fixed, I did an in-car ECU fuel adjustment. This was crucial to making it work! I now enjoy a very response engine that gets good MPG. I also had a flat spot in power (more like a trench) in power when I would ease into the power when staying with traffic speed, that is gone. I’m not sure what ECU you are running but if you really what to get it tweaked properly you need to do an in-car on the road test to get it dialed in.
Another simple thing that can cause havoc on how your system is running is the MAP sensor, have a spare and swap it out.