Bass cutting out intermittently

Ok here's the problem folks; my car audio troubleshooting skills have failed me here. I have an '02 Sunfire with the following components - Pioneer DEH-P7400MP h.u., Monsoon factory amp powering factory speakers, MTX Thunder4202 powering a Coustic BP104 sub. Here's the problem - I've had this system for about a year and a half, and within the past 2 weeks the sub has started intermittently cutting out. It will cut out for a few seconds, then back on, and then off again. The ground and power supplies are fine, the LED on the amp doesn't go out when the sub cuts out, and all the connections are good. The amp's not the least bit hot when it does this; the only thing that is remotely hot is the head unit. Any ideas? Thanks in advance.

Could simply be the sub is in the process of failing.  They do wear out over time, especially if they are pushed hard.