Bass cutting out

I had the exact same hookup in my car that I have in my truck and it never cut out, but now it just quits at high volumes and comes back in a few seconds later if I turn it down. My amp is not going into power protect mode and my subs are brand new. I am in the process of trying to put in a better ground just in case that's the problem, but I thought I'd post here to see if you guys had any other advice in case that's not it. I have a JBL 600.1 Grand Touring amp and two 10" Powerbass M104 subs.

Bump. I tried to fix the ground but it didn't do anything. I'm currently trying to find a better place to ground it this time, since the first time it was just cause it wasn't connected well. I reallllllllllly don't want this to be a problem from literally day one. Just a month or two of good sound without problems lol.

Bump

Bump