Hey scotty, I have a 2008 chevrolet express 3500 passenger extented van, with the big old 6.0L Vortec gas V8, it has 275,300 miles on the clock. But the idle is rough and the speeds are low at around 500 RPM, the vehicle shakes at idle, what can be the issue?

I've also noticed that just like many other chevy's, the oil pressure/gauge is very low at Like 10 PSI at idle and approximately 20/23 PSI at highway speeds, will changing the oil pressure sensor fix my issue as I know it did for others with this issue, and could that be the fix for the low idle and shaking business or is that just normal for an engine with that mileage? 

Other then that, the truck drives fine and shifts more or less like a dream, never had any major mechanical issues besides brake rotors warping from riding the brakes with the heavy weight of the van. And like tire pressure sensors going bad as well as the power steering pump, but I think this engine is practically bullet proof, the frame is still solid and other then that it's a horse!