Got the new (same 3932) plug into the engine where the lower temp header is and it still runs rough. Then listened with my stethoscope tool on the fuel injector on the left side of engine and on the right side of engine and did the same listening on the left & right heads. But each side sounded the same. I might pick up one of these spark plug wire testers in the link below just to be sure I have spark through the wire. Probably next step is to find my compression tester and do a check. Its around somewhere because I did my old Maserati Biturbo years ago. I did another quick header temp test and the one was still lower than all the others. I wonder if some of that may just be the header being closer to the engine bay opening & has more circulation to fresh air and therefore may just normally have less temp than the others. Right side did the same with lower temp near the engine bay header although not as noticeable as the left side variance. Next time I pull out my other Panteras I'm going to check the header temps. I still think its too much heat variance though.