Well I checked the vacuum it is at 10in Hg when the miss starts at around 3000 rpm.Shouldn't that be higher? I checked the wiring harness on the engine that goes to the injectors against the schematic and the color of the wires to each injector match up. I also tried unhooking the fuel pressure regulator vacuum and plugged it off to give the injectors full pressure(39psi) at high rpm, but the miss is still there, note: the backfire only seems to happen when I'm accelerating under load( low vacuum?)