it might have something to do with egr valve. i havent played with the timming at all since i put the engine in, but its running at 12deg. ive also played with the fuel pressure and i didnt notice a change
Possible fix!!!!!: I just changed my O2 sensors and I'll be damned if it didn't buck, jerk, miss, pop, or backfire AT ALL. The O2 sensor on the drivers side was coming loose out of its socket, so I'm sure that was a problem. 2 new Bosch O2 sensors for 80 bucks total fixed the problem, it takes like 10 minutes to replace them, too.