rough running
 

Several years ago I built a crate 350 with 125 cam. I am 77 with some physical problems and have only had car out a handful of times. Idles ok. When i step on gas it hesitates increases speed sometimes coughs a little but never has good torque. I have replaced the coil and distributor new wires and timed 12 Btdc. Little improvement. Has a light backfire. Could it be some kind of short in my wiring? Is it possible to not have lined up cam correctly? LOST