I am having issues with after market distributors. It has baffled the best mechanics I know. 97 Silverado 5.7 70,000 miles into a crate motor and trans, I replaced every switch and censor on the motor swap but used my original distributor. Ran awesome for 68000 miles and the started to give me codes about misfired. A friend mechanic suggested I change the distributor so I did. Bought new one at Advance Auto parts. Bam! Problem solved. Ran great for two days and then went into trying to start in full advance. Not gonna happen. Took the distributor back to Advance and they gave me another. Ran 2 weeks, Bam. Same thing. Had 3 new ones from Advance and all 3 done the same thing. Got fed up went to NAPA got their premium distributor. 2 days in running great, but do I have to wait on the same results or could it be my computer doing it. Help me before my head explodes... Thanks in Advance. (No pun intended)!