I had the same problem, im know this info wont help you at all. But if it was really low humidity I would never have a problem. But once it got really sticky out again, misfires like crazy. I could never figure it out, I had a new ignition coil, new wires, new spark plugs. So I decided what the hell, I bought an accel ignition coil for $20 used. Installed it, havent had a single misfire since.. Im sure this isnt the case with yours, but I thought I might shed some personal experience.
