Do I need a new radio or is the wiring mess up?

My sound system in my truck is messed up to high !&&* and I’ve got no where left to turn to some I’m asking for help.

It’s a 1996 Chevy C1500.

I was hoping someone out there has the right wiring diagram for my truck to go off of to double check the wiring in it. I’ve looked all over the internet and every single one I find is different from what I currently have in my truck. It’s a non amplified system, aftermarket radio. Factory harness has been cut completely out and had a new radio hard wired in. Isn’t getting a constant power so radio resets itself every time I turn the truck off, front speakers only work and most of the time sound blown even though I just literally replaced them. Sometimes they sound perfect for a few minutes then immediately go back to sounding like they’re blown which is confusing me and I can’t figure out why.

Any help would be really appreciated y’all. Like seriously, y’all have no idea how badly this has been driving me crazy.