help with 91 explorer?

just check the oil it will be fine for the next couple of months, the oil pressure sending unit is going bad that's why your oil gauge is flickering

You never said it. But when you stick measure your oil, it depends how accurate your reading is the way you measure it. If you do it right after you drove the car and with the engine hot, you won't get an accurate reading and perhaps lower than the actual amount sitting in the pan. This is because a hot engine still draining oil from the upper valve chambers and it's take a while from the oil to sits. The most accurate reading is with the engine cold just before you stat it. You don't even need to wipe the deep stick.

You don't have 20 dollars to get an oil change? Really? Can't you go give blood or sell some personal property on ebay or the like?

It's not a frivolous thing...you can cut back in other areas (i.e. groceries: buying generics) but at the end of the day if you don't keep your car running you're going to be walking.

Oil pump... This vehicle must have high mileage..... if that's the case dont waste money on it. A oil change wont necessarily help. Im sorry this has happened.

Perhaps you need to check the oil level with the dipstick under the hood.

Maybe it's low on oil?

Add a couple quarts before you ruin it and have to buy a new engine.

That will happen if your engine runs very low on oil. If it hasn't been changed in a long time it will use (burn) more than usual. If you keep driving it that way you will ruin it.