Is my motor going out?

20psi when driving is low. Your engine is probably worn. You could try to replace just the oil pump.

Low oil pressure is serious. Check your oil sensor and oil pump.

I believe the 351W began in 1961 and was discontinued in trucks around 1996. That being said, the engine may be a little long in the tooth, 22 years old now when discontinued. May be a rebuild by a competent shop is in order. I think one can still be acquired via Ford Racing, but I would suspect at an extraordinary price.

I just changed the oil and filter but for some reason when I push on the gas the oil pressure goes up and when I get off the gas it goes down? I see that there is a cord hanging down but can't find where the hell it goes. If it for the oil sensor I can't tell I can't even find the oil sensor. My dad had helped me with the filter and we looked everywhere to figure out where it goes. But how bad is it if the gas pedal messes with the oil gauge. How long can I drive it that way.

If you want to throw an inexpensive part at it, go to an auto parts store and look at the photo of the oil sending unit. It probably cost about ten bucks. It will screw into the engine and have an electrical connection to it. It is a common failure and installing a new one will let you see if the needle steadies out. If you want to check the pressure you will need a oil pressure gauge (available at auto part stores). You will have to surf the net to locate the proper pressure reading for your engine. As for how long you can drive with the problem? Depends on the problem. If it a gauge or sending unit, and the pressure is correct, you can drive it until the old engine finally dies. If it is the oil pump, you can drive it until the pressure gets so low the engine seizes or blows.

Also I cannot find the oil sensor I have watched YouTube videos but still no clue the o ly other thing by the oil filter is a silver bell looking thing but nothing like they show.

What you refer to as the "oil sensor" is the same as the oil sender or sending unit. It is silver in color when clean with electrical connection. Usually takes about a one inch or so socket to remove it.

This info was taken from my repair manual for a 1991 through 2001 explorer 5.0 v8 engine. Specification for oil pressure is between 40 to 60 psi with engine and oil at operating temperature and rpms at 2000. Suggest you purchase a fairly descent oil pressure kit with adapters (probably around 50 bucks) Remove sending unit from block. screw in gauge via hose applying thread sealant to prevent leaks. Start car and let idle until up to operating temp. While holding idle at 2000 rpms read gauge. If under 40 psi or pressure bouncing change oil pump. If pressure within specs, you're ok. If pressure fluctuates between normal idle and 2K rpms your sending unit is probably good also. If only a very slight fluctuation in pressure between normal idle and 2K, spend another ten bucks and install a new pressure gauge. There may be two different one's for you car depending if you have a idiot light or gauge which moves. Make sure you get the correct one.