my 96 had both of your problems
Adding more grounds to the dash gauges fixes the gas gauge/lights on problem.
All the gauges have 1 ground wire, that piggybacks from gauge to gauge and them goes elsewhere to other electrical items. I added a new ground to the left side and right side gauges....Problem gone
The 8.3 has known issues with the fuel shut off solenoid not opening, partially opening and or opening but not able to stay open causing the fuel to the inj pump to be shut off...thus causing engine to die...they usually always start right back up...just as yours is doing