Having a strange electrical? issue with Truck

[Clayhead]

So a few weeks ago after hauling a skid of fertilizer, driving 20 miles and going to Lowes, My truck suddenly wasn't getting gas. The sending unit/fuel pump quit. No problem had it towed to a local mechanic shop. When they tried it it worked fine. So I cautiously drove the truck a couple weeks with no problem. Then Tuesday I pulled up to a stop sign and it lost all electrical power. Just shut down, no light, no nothing. Called a tow truck and while on the phone the power came back. I quickly restarted it and drove it home. Yesterday after the truck was setting in my drive for over 24 hours went to put the windows up, no power. Checked back 2 hours later and everything was fine, even started it just to check. What the heck beside the ground and battery should I be checking? ECM? any ideas appreciated.