So I was attempting to cure the small misfires that I was getting at idle this summer, I installed new exhaust gaskets, a new O2 sensor, and sealed the engine up tight for vacuum / boost leaks but I still had a misfire that would show up after the car had been running for awhile. By that I mean not just after it got up to temperature but after drives longer than half an hour or so. The only thing that seemed to help was reducing my plug gap from 0.28 to 0.24 on BR7ES plugs, but even that wasn't a huge improvement.

Well fast forward to the fall and my misfires have gotten better and better as the outside temperature has dropped, then today with the temperatures back up close to 20 degrees the car was missing again. So with all that evidence I'm thinking that either the PTU or coil packs must be getting heat soaked with the higher under hood temperatures in the summer (coolant temps have remained the same in the colder weather).

Does this make sense or is there something else here I'm overlooking? I'd like to try to diagnose this without swapping in alternate parts so if anyone can think of a method of testing the components other than trying to get the multimeter on them when they're roasting I'd like to hear it.