I just finished my new engine/tranny install last night. I bought the whole engine/tranny with most the mods from a kid who had it on a show car and then wrecked it. There is no damage that I could see. He had a blower on it too, but it is not on there now. It has all the mods in my sig. Anyway, when it gets halfway warm it starts popping and backfiring to the point where it will basically die. If I hold the idle at about 1500 it doesn't backfire at all, nor does it backfire when I am driving down the highway, but definitely lacks power. I tried adjusting my timing, but it didn't help matters, I tried everything from 10-20 degrees, but still pops/backfires. It is running very rich as I can see the black on the conrete from the exhaust. Also, I kept getting shocked from a wire on the distributor when I was adjusting the timing, pretty sure it was the coil wire, but this might be something unrelated . Could the backfiring be plugs, wires, or maybe the coil, is this probable? I am waiting for O2 extensions for my sensors to come in, should be here tomorrow, but I wouldn't think that no O2 sensors would make it backfire like that. I had a feeling everything wasn't going to go too smooth, Murphy's Law, ya know I already figured out that I cracked a nossle on the heater core and found coolant on the water pump also. When it rains, it pours. Thanks for any input at all!