1997 Pontiac Grand Prix I suspect there is an electrical pr

I got this car in the beginning of August and it has run great up until about 3 weeks ago. I had someone install my amp and subs and ever since then, my car has been having a problem. The fuel pump fuse keeps blowing. I brought it into my regular mechanic and he is the one that discovered my fuel pump fuse was blown because my car wouldn't start. He did not however, figure out why it was blowing. He found nothing mechanically wrong with my car so he sent me on my way with a few extra fuses in case it blew again. We had hopes that it just needed a new fuse. Well unfortunately it is continuing to blow so its more than just a worn fuse. I assumed that it had something to do with my amp install so we completely disconnected my amp but it is still happening. It just blew again today but it went a whole week without blowing until just today again. It usually has been blowing once every 2-4 days. I've also noticed its only when you press the gas. It happens when you push the gas from a stop at a light or stop sign and once you push the gas down and get going, the car stalls. I can start my car and let it run to warm up and it will sit and run just fine for 15 minutes, but then after I pull out and get going, the fuse blows. I don't understand why it will run until you start driving? It doesn't always happen right away after I get driving either. Today it ran for about 15 minutes, then I drove for about 2-3 minutes and when I made a right hand turn, and pressed the gas to go, it blew. I then have to pull over, pop the hood, pop a new fuel pump fuse in and my car starts right back up like new again. I can't afford to be bringing my car from one mechanic to another and paying for diagnostics to be run and then still having the problem. I already paid my mechanic $75 just to look at it but he doesn't know why its blowing. He said my entire fuel system is working properly and his conclusion what that the guy that did my install must have damaged something electrical in my car when he did the install. Even though I disconnected the amp completely, its still happening. Its possible that it just coincidently started happening right after the amp install and has nothing to do with it but I doubt it. Do you know what the problem could possibly be?