Okay the car has been running perfect and never had any issues with anything. I went out the other day and hopped on freeway when i punched it, there was some misfire for first time ever and it does it when boost and rpm's are high.. never had this problem... so same thing next day.. changed plugs and went from the ngk 8 to 7 just for testing purposes.. i am running 23lbs boost.. well everything ran great.. well time to put gas in car cause i was almost empty.. went and put sunoco in it and got on highway at night time and about 3 minutes later when i punch it... misfire occurs worse then ever. I dunno if this has to do with cold,bad gas,or spark plugs/wires..etc the car still pulls hard during "misfire" but only does it at high rpms and high boost.. it will hit 23-24 lbs then when misfires the boost will drop a quick .1 sec my boost guage looks like a rev-limiter the way it moves.. "best way i can describe it". i guess im gonna try changing out plugs again and i got that sunoco out.. any input will help. my following main mods are

walbro 255
brian crower 280 cams
brian crower valve springs
arp head studs
880 cc injectors
perrin fuel rail
stock turbo
tial bov
front mount
aem standalone (tuned by ams)
3 TBE just resonator on there right now.

Those are really just the main mods that make the difference.. like i said never had a problem with the car.. when i took old plugs out the were kinda whiter which from my exp means car is running lean right? maybe since its colder out and running 23-24 lbs boost maybe car is starting to lean out? I am 'newer to evo's' and it is the first time running car in "colder" temperatures i guess.. just freak how i changed plugs and everything was fine then i put sunoco 94 in car and car starts "misfiring" like crazy. any help would be great< thanks

 

also it is an 2003 forgot to throw that in there

 

mmm how much colder weather are we talking about here...?

 

What did u gap your plugs to?

 

^^^^^^^^^^^
That's actually what I was going to ask.

 

well from 70-80 degrees to like 50-60 degrees.. the new plugs were gapped to
.028 the ones that were in there were like ngk brp8 and i put in ngkbrp 7 and gapped at .028 the car ran great all day then at night put gas in it that night thought it may be gas...

 

gap them tighter. like .023 and the the BPR8ES

 

what is the gap supposed to be then? what will making gap tighter do?

 

A quicker, more intense spark with a shorter gap

 

Does the cold air effect anything at all? just weird how it happened i guess. so ngkbrp8es is what i should use and gap them at .023?