Memphis car audio amp problems?

[jbomb816]

I have a amp that worked fine in someone elses vehicle and i put it in my ford f 150 with the 5.0 motor in it and now the power stays on but the bass will cut in and out and sometimes it wont work but sometimes it stays on any suggestions on what this could be ive worked on these things for a while and this is the first time ive been puzzled ive checked power and ground and remote differnt amps work but this one is the only one i seem to have problems with