I have a 1986 T/A with 305 4bbl. with 103,000 miles. I installed AC Delco Rapidfire plugs and autozone wires in my car in 2004 (roughly 80,000 miles). Car ran good, but figured it was time to change out plugs, wires, cap and rotor. Bought new cap and rotor, AC Delco OEM plugs, and switched out wires under warranty. My car now has a miss that is slightly noticable in idle (kind of like a very low pop every 3 or 4 seconds). Runs fine accelerating and still has lots of power like before. Sometimes when I cold start it, the idle is erratic and I can feel and hear a slight miss out of the exhaust. I gapped the plugs at .035 (label under the hood). The only thing I did differently was route the plug wires on top instead of underneath. I broke the plug wire holders and routing the wires this way was my only option. I tried to keep them from over-lapping each other but most of them are close together and over-lapped (not sure how critical this is??). I turned up the idle to around 750-800 rpm and that has helped with the erratic idle, and the miss seems to be almost un noticable now, but still there. Not sure what else to do?? Just my luck......try to do something good for my T/A and now runs worse than it did before, but still very much drivable. Any help is much appreciated!! Thanks.

 

What cap and rotor did you get?

FWIW, I had a buddy that did the same work one time and couldn't even get his to start- ended up being a bad NIB rotor.

 

I bought the cap and rotor from O'riellys. I believe the brand was master-pro. I'm taking them back and getting the borg warner set with brass contacts. Hopefully this will work better.