About a couple weeks ago my truck started cutting off. I could leave it in park and give it gas to keep it running but it has a real loud knocking noise and runs real rough. I'm not losing any oil or coolant although I need to replace the thermostat. A mechanic says it's misfiring on all the cylinders. I don't know if this is the same issue but it had a rattling noise but it didn't sound like it was coming from the actual engine. The night before the rattling noise got louder. The mechanic said the oil pressure was low but again I wasn't losing any oil. It's also not spitting out any codes for the problem.

 

How many miles on the clock? Low,, did he give you a test pressure?

Ever over heat, coolant loss, missing oil level etc. it doesn't need to leak oil to have or suffer from low oil pressure. If you suspect base engine problems, sometimes an oil sample taken at the drain plug, or removing the oil filter and cutting it open may show suspended and collected metal debris. A good start point to get an idea if anything has gone/going bad internally. Surprising if a misfire, no present codes. Battery been disconnected, or memory cleared?

 

Never overheated. No coolant loss. It was missing close to a quart of oil. I'm guessing he tested the oil pressure because he said it was low.