I had a wiring mess with the old radio in my 1995 F150. So I ordered a Boss Audio 612UA radio and installed it this week. I ripped out all the old idiot wiring that was crammed in the front of the fuse panel under a couple fuses. I bought the appropriate connectors and hooked it all back up through the factory harnesses. Everything works great on the radio, but the sound starts out fine, then drops down to a dull/muffled sound, then back to loud and clear. It only lasts about 5 to 10 seconds at a time.
If anyone has an idea of what is the best way for me to troubleshoot this problem I would greatly appreciate it.

Thanks

 

Sounds like you have a capacitor leaking on the amplifier. I'd take it back to WalMart and exchange it for another radio.