Fuel gauge/oil pressure gauge acting flakey

[tguthrie]

I know about the fuel gauge sending unit problem and pay little attention to it since I don't trust the gauges anyway. Now, my 1999 1/2 GMC Sierra has an oil pressure gauge that will go to 80 (max) at road speeds and drop back to 40 at idle. It will jump around at idle at the same time the gas gauge jumps around. I turn the engine off and it may not drop back to 0. Are the issues related? If not, what do I need to be looking at. Running out of gas won't break the truck. Oil problems will. The other two gauges act like they should.