if the amp is moutned properly and just getting too hot, it just may be its not getting enough air across the heatsinks.
I have a pair of new cage fans designed to cook amps in cars if youa re insterested, they are about 2 inch radius rans, like a big over size computer fan, you moutned one on each side so its push pull across teh heat sink, and it should take care of the overheating problem.
30 shipped for both...
b