loud thumping when amp is on

Alright.. so here's my problem. I have 2 kicker xpl 15s and a spl 1000w amp, a kdc 138 head unit, Recently i took my truck in to have the transmission rebuilt so i took out my head unit and my amp/subs and all the wiring so it wouldn't get stolen.. when I got my truck back when I hooked everything up there was a mild staticy noise which got louder when accelerating. At first the noise only happened when my truck was on, then it started doing it with just the switch on and the ignition on. So I decided I would redo my wiring and see if I could see anything wrong with it, but there was nothing I could find. afterward when I turned on my truck the subs started making a loud thumping noise and it was taking a ton of power, my headlights were almost going completely off. I tried grounding my amp and head unit to the same spot which didn't help and I tried another set of rca's which also did nothing to fix the problem.. so now here I am asking you guys what my problem could be. Sorry about the long paragraph..

Forgot to mention, my truck is a 1999 Chevy Silverado Z71

Yes, that, plus turn down your amplifier's gain.Support the12volt.com