Hey I was driving my truck one day and it was.

You're supposed to stop the engine as soon as the oil pressure drops. Damage will occur within a few seconds. That is evidenced by the inability to maintain speed. If the engine still runs have the pressure checked with a mechanical gauge. If it's low, suspect it will need crankshaft and connecting rod bearings and a crankshaft, and most likely the pistons and cylinder walls are scuffed. The valves in the cylinder heads should have survived but the lower end will need to be rebuilt. The engine did good if it has 290,000 miles on it.