If my truck sits for a couple days I get surging and erratic idle when I first start it. Fass seems to show the proper fuel pressure? Leaking injectors?

Probably losing prime someplace, did you redo your fuel system yourself or just parts of it. Or have you ever touched it. When did it start just recently or always been this way, what was the last thing you messed with fuel related

Nevermind my fass is intermittently working and now its just dead... Great. Anything I can check on the system besides the relay and grounds?

You can jump the relay and see if it stays on. Check power supply from ECM to repay. Could be just a bad relay, I changed mine to protective one, thanks to @IBMobile

It actually was the relay. Could you link me to a protective relay for the fass system? Thanks man

https://www.12voltplanet.co.uk/relay-guide.html

Pretty sure most part stores will have something

56 minutes ago, Dieselfuture said:

https://www.12voltplanet.co.uk/relay-guide.html

Pretty sure most part stores will have something

No I bought a new one from the parts store, but I thought you were talking about one that would insure the elements better.

I'm sure there are waterproof relays that are surge protected also, main thing is to make sure that's has a resistor or a diode

To water proof a relay you can coat the bottom of the relay with either a silicone sealant or a two part plastic epoxy.