It's not your pump, that's for sure.
I've run the same 100 psi shurflo pump for over 10 years, all day every day. No issues.
Where's your ground? Could be dirty. Check connectors, don't use those blue crimp connectors, use bullet connectors at the very least.
Hook up a fresh battery as well. In fact, forget that, I've used nothing but the van battery itself for nearly 10 years. It works much battery. Hook battery charger up overnight, wire in permanently, just in case you do a short mile day.