Rough Idle, Smoke Out Exhaust

[FourWeeks]

Started my car up this morning, noticed a sort of rough idle. Almost sounds like I'm cammed but I definitely am not. No CEL, just fixed my boost leak. Figured it was because of cold temperatures (40 degrees) so I let it warm up, idling wasn't as rough as before but it's still noticeable. Oh well, probably just being a hypochondriac. Cruising along I notice I'm backfiring way more often than usual. One of my buddies behind me mentions white smoke coming out of my exhaust and says something about blowback issues. I go WOT to test his theory and sure enough I'm popping for a good three seconds during decel all the while white/blue smoke is pouring out.

I limp back home and check oil, doesn't look like any coolant is in there. Hoping it's just bad plugs and/or coil packs. Plugs are NGK Iridium BKR6E (I think) gapped down to .025 on a stock setup. Cylinder two coilpack has white residue so I'm assuming it's failed. I posted another thread about a boost leak and mentioned replacing them but never got around to it. What do the Zilvia bros think? Bad plugs/packs? Bad turbo? Blown headgasket?

[Kingtal0n]

when the smoke starts, ALWAYS start with a compression test and visual inspect of the plugs and cylinders (shine some light down in them and compare the colors of the pistons).

You might also want to jiggle the compressor wheel a little bit (if you have a turbocharger) you said coilpack so I am guessing sr20det redtop or something.