Originally Posted by kbolden50
Start off give you some info on the car it's a 1989 ford mustang started as a 2.3 and swap it for a 5.0 connecting rod bolt broke and cracked the block got a engine out of a 97 explorer with gt40p heads fake cobra intake some upgrades from the 5.0 stock checked the crankshaft end play everything looked good so I change some gasket and seals didn't want leaks the motor starts and runs but not smooth a little shake and I get a small back fire sometimes I did the timing and checked the wires no vac leak I can see or hear going to start it and spray water on the lines to check them want to know where and if you can get your sensor tested And the ECM tested
Did you use the ECU/ECM from the 5.0?
Wiring harness changed out to the 5.0?
MAF and injectors matched?
The shake and backfire sounds like a timing issue, double check the timing and make sure you wired the plugs correctly to the 5.0 HO 13726548 firing order.