Have a 2011 Chevy Silverado z71, have spent 1000 on front end due to eating tires, now the oil pressure drops, no clatter, are pulling the manifold, alt, all wires and lines, but to get the screen you

The screen they're talking about is at the end of the oil pickup inside the oil pan; it could be blocked, but if it is, you most likely have bigger problems. You'll know when you drop the oil pan; if it's full of debris the motor has begun to self destruct.

Have you checked the wire on the oil sensor? If it is lose that will cause the problem. The sensor if bad will also do the same. It is around 25 dollars to buy and is far cheaper than tearing down an engine that does not need it. When the work on the front end was done, I'm sure a lot of wrenches and other tools were moving around and a wire just could have been knocked lose. Don't spend a ton of money until you are sure the problem exists. I think the sensor is on the top left rear of the engine, But it could be elsewhere so check first.