EPC/ misfire (IS38)

I recently went is38 stage 2 from EQT. The weather is getting colder outside so it takes longer for the engine temp to rise. I keep getting an EPC light and the car misfires like crazy. Does the oil being not at temp cause it to do so or could it be something else. (Have all supporting mods + 1 step colder plugs from NGK) one thought was it’s the plugs but I may be wrong. Anybody have any idea/ gone through the same thing?