i have a rockford fosgate amp, sometimes have the same problem. only during the day. but its over 100 degrees here most of the time now. when i put the rear seats down, no problems at all. it only happens very rarely for me though. i have my amp mounted on the back of my sub box, with about 1/2 inch spacers between the box and the amp. my solution is to go to a computer place, get a couple little fans,(small ones that go on the processor for a computer) and hook them up in between the amp and box to help air flow. dont know if this will help you any, but maybe it will give you an idea.