My car has an upper rpm misfire, no codes. I'm almost positive it's the spark plugs which are the copper Autolite 764's which have about 20k miles on them. Should I replace them with the copper 764's again or should I get the copper Autolite 103's? I do have a chip with advanced timing. Basically I just need to know if the 103's are good plugs...

NGK V 2 steps colder

I will only use Autolite plugs, no Japanese made plugs are going into my 4.6 DOHC.

i use ar103 on and off the bottle
if you need it colder than that ar474 is about 2 steps colder than the 103
ar473is even colder and ar472 is really cold

I will only use Autolite plugs, no Japanese made plugs are going into my 4.6 DOHC.

Good man!

its big with the cobra guys so hell why not. I dont even use autolite in my mower