Hi V8 Buick, I replaced wires, ignition coil, ignition module, cap / rotor, spark plugs, fuel filter and air cleaner; and the car is running like crap. Cylinders 4 & 6 are a little rich, the others are fine. The engine idles a bit rocky, the car sputters on take off in drive and reverse. It also back fires while driving whether on or off the throttle. I cleaned the carb as well. I'm planning to install exhaust and header but hopefully I can sort this issue before installing the exhaust and headers. Any help is always appreciated. Thanks.