SO heres my story. Going along not paying attention and ran the pickup low on fuel got fuel switched to other tank but engine started hammering, running rough, missing etc, Then it died. Got it started back up and home, filled both tanks. Replaced fuel filter because of running to the bottom of the tank. Got it restarted but same symptoms, revving up it felt like it ran better but still really rough. Shut it off and tried to get air out using schrader valve.

Now after doing that I seem to have a no start, charged batteries over night with no result.
Cleaned FPR screen, it was dirty but still no start.
Checked fuel pump and we have plenty of fuel coming.
Rpm's seem to move when cranking
Oil Pressure gauge comes on while cranking
NO smoke while cranking
Im at my wits end at the moment......