The OEM IAT sensor is slow response so I doubt that that temp change would be it. +1 on trying another good distributor. When they are going out, the temp has a big affect on things.

The MSD stuff is really hit and miss, but I have had good success with the Digital 6 and Digital 7 + boxes. The older, lower level stuff always seems to have issues. My car made 700whp with the digital 6 box, blaster coil and Hondata S200.