What's wrong with my car stereo?

When I got off of work, I plugged my iPhone into my AUX Cord in my receiver, my music is playing on my iPhone, but my music through my car speakers is chopping and pausing constantly. But if I turn it down lower, it plays, then when I leave it on that volume level after awhile, it does the same exact chopping/pausing effect, so I half to keep turning it down lower. I replaced the AUX cord, so it can't be that. Is it the actual receiver I need to replace? Or where would I go to get that looked at?

Test it with someone else's cord and mp3 player, respectively. If it does it with other players and cords too, take it to a private stereo place, they won't charge much. If you don't have one, try Best Buy's install bay. They will likely charge a diagnostic fee, but may not if they aren't busy. If turning the volume down quells the problem, then you must have a short circuit happening. Higher output=higher voltage=higher tendency for electrons to jump.