Ok guys...I just replaced a known bad opti with an MSD one. I also changed the plugs, ICM and fuel filter. The car developed a slight miss and backfire and is running like crap. I scanned it and pulled a DTC 64 - Right O2 Lean. Will that cause a miss and backfire at idle. All the plug wires look good. Also, at WOT, it spits more black smoke than usual. Im assuming this is the problem, but Im new to fuel injection so I dont know. Thanks for any help.

 

With the O2 reading lean, the PCM will add more fuel. More fuel will foul the plugs causing misfires. Look for burned wires particularly if you have headers where the bundle of wires goes from the top of the right inner fender toward the bottom.