So, got a 99 GTP, and every once in a while under 70% or more throttle, 2nd gear or higher, it gives what I would call one @#$%ing hard miss with no SES light or codes when it's -20F outside or +100F. Here's what I know of the motor/trans; it looked stock but replaced a drilled 165* thermo with 180, wouldn't warm up in winter in nw Minnesota and I didn't know better, leaked oil everywhere and blew every oil gasket when I first used royal piss, wont use that junk again, when all gaskets replaced including supposed recalled ones(they weren't), the mech said I had internals he didn't recognize as stock, and SC pulley was beat up.
What I did: first two things, headers and dp, CAI, U-bend resonator delete, used Corvette 3" cat and 3" pipes straight to Y pipe, and factory pipes to fac mufflers. Second was coils/wires/plugs; msd/msd/AL iridium xp's like factory says. New fuel pump/filter, flushed it all the way to rails, tran filter, cooling system flush, PS flush, brake line flush plus cross drilled/slotted 12" upgrade. Replaced with 33# inj. It did have a 1.0 from zzp that I didn't know, dealer fixed that @#$%&*... so my question is, plugs?104's waiting, arms are too big to reach, fuel? We only have 91 or 100 race gas. Fuel pump wired for more V, and volt booster. The msd coils have been good, I think, 20000 miles on them, or ICM? no ses light tho. Confused and frigid, any help?