took my '87 shadow for a spin today and felt like doing some wot pulls on it, and when the car is pulling hard through around 3000rpm it backfires/cracks with a bang and will stumple and not go any further in rpm's. is there any common issue with these cars that will cause this that i should be...

This is a continuation on a previos thread Odd Behavior that i have but since it deals with a new set a problems and no one ever reads all the posts im posting the most relivent information in here. After installing new engine into my car, it ran great, got it home 10miles later and let it sit...