Gas gauge not working and oil pressure goes to 80 pounds

The oil pressure gage starts bouncing around allot.

Check your oil level

Well it could be the sending unit for the gauge.
But odds are the oil pump or engine bearings are worn out.
As the engine warms up, the metal spaces expand and the oil gets thinner. The oil pressure drops some under normal conditions, but not more than 10 or 15psi. Normal idle pressure with the engine warmed up is probably 25psi.
You could check oil pressure with a mechanical gauge to make sure its not the sending unit.
Once the oil pressure starts staying below 20psi for long periods you'll start hearing noises.

Either you have way to much oil in the truck or the pressure switch is no good.

Another gauge needs to be connected to the car to check that oil pressure sensor or the gauge itself is not the problem.

If an independent gauge shows the same readings I would suspect a sticking oil pressure relief valve.

Bad sensor

80 lbs is good. It's more like around 50, it's probably the oil sending unit. Take a look at it aand make sure it in't leaking. If there is any oil covering it and none coming from above it is leaking. I don't know engine size, but they are usually located around the oil filter.

replace the oil pressure sending uint on the engine.

the oil sending unit that screws in the block beside the oil filter may be faulty,
the worst thing would be the oil pump its self the regulator valve on it

sounds to me like you have a bad oil pressure sinding unit