Q: Electrical Issue (I'm assuming)

I just recently purchased this truck. The former owners took it into the shop right before I got it, to fix a burnt out headlight. The first alarm once I got it was that when I turned on the lights they (dashboard and exterior lights) flickered like a strobe light, and then just wouldn't turn on after that (including the interior cab lights) After that happened I let the truck sit in my garage, and that night I went out to the garage and noticed that the headlights were just barely glowing, and glowing an orange color. So I disconnected the battery and let it sit for the weekend. On Monday I hooked it back up, and everything worked perfectly, but now every so often it shorts out and then the lights don't work, the door locks won't work, my four wheel drive goes out, and my wipers only work on full blast. I've just been disconnecting the battery overnight every time this happens. But I'm looking for more of a permanent fix.. Any Ideas??

My car has 150000 miles.
My car has a manual transmission.