Spark plug AC DELCO or OEM Audi

Only use the factory AC-Delco 41-987 plugs.

I paid $42 for the ACDelco iridium plugs, $45 for the ACDelco pro wire set.

GM products run best with AC Delco plugs, just like Ford products run best with Motorcraft or Autolite.

I did put ac delco factory iridium plugs from rockauto on mine at 100k.

While I had the coils out, I replaced the plugs (used ACDelco double platinum professional grade, proper gap. No NGKs were available). After I replaced the coils, the misfire code(s) went away for a few days.

Put them into a stock '87 Subarban and tore my hair out thinking I messed up the wires 'cause it idled so bad. Really, like I had two wires switched. Put the old worn regular AC's that I just took out and it idled perfect.