3 mtx subs on alpine amp, shuts off

so i got 3x 10in mtx's hooked up to a 1000watt rms alpine amp and it works and sounds fine with like 3/4 of the gain up, but when i turn my cd player to 30+ volume (40 is max) for like 10 mins the subs stop working.. but when i turn my cd player off and back on, the subs work again? why does this happen?should i set the gains lower? or why is the amp shutting off when i try to bump for longer than 10 mins?

This happens because the amp is overloading, probably because the gain is set incorrectly and/or the speaker load is too great, or possibly because the system voltage is dropping too low.  As was asked before, what is the total speaker impedance you are putting on the amp?  And I suggest reading and following the "How do I set my gains" sticky thread.

all 3 of the subs are 4 ohm svc.. so i cant really wire them in series.. i think it is putting out a 1.3 ohm load?

and also if the amp is overloading.. if i set my gains lower would it stop doing this? like i said, it works fine for like 10-20 mins.. after that it starts shutting off... but once it starts shutting off... it will keep doing it if i try to turn it back up.. unless i let the amp cool off for a while.. than i can get the 10-20 mins again. i think its overheating maybe? if i keep the volume at like 22-25 it works just fine for a long time.. but once i start getting in the 30's for a while it will start shutting down

He meant a 4 ohm load