How do i keep my AMP from Overheating?

i have a 875 watt jensen amp powering 2 12'' jensen JPW124 subs, and i drove 4 hours and the subs kept going off, i turned the subs off for a few minutes and then turned them back on and it worked again, this kept happening for the entire drive. i touched the amp and it was scorching hot, how do i keep it from overheating?