I have a 97 z28 with which i just had installed a hotcam, mildly ported heads, msd ignition (no msd coil). long tube headers, removed cats, and rr's. Since I have had these installed, when I hook the computer up to the diagnostics it shows that all 8 cylinders are misfiring.... its not missing terribly but is more noticeable sometimes more than others. has anyone else had this happen? Anything I should look for first? ANY help would be appreciated.... thanks!

 

Dirty optishi+ I would guess. When I took mine apart last year it was coated with oil inside. Took care of the misfiring when I got a new cap & rotor.