i have a 95' jeep cherokee 4.0. whenever i accelerate the oil pressure gauge will go up and then back down when it shifts, then does it all over again until i stay at a constant speed. could this be the oil pump maybe? any ideas are welcome

 

Normal.

 

How far is the needle moving? Is it moving slightly between shifts or is it swinging far to the left and gradually moves to the right as the RPMs increase?

If it is a slight movement, then Bustedback is correct, normal. If it's more of a swinging arc, then something is out of tolerance.

 

the needle stays around 40ish, maybe a little past. but i went out of town yesterday and around 60mph the needle was around 80. but going back to the needle- i'll accelerate and the needle goes up to about 80, then when it shifts, goes back down. usually if i take it easy it won't do it so bad.

 

The sending unit may be bad, I doubt there is anything wrong with the engine.

 

ok, so you don't think it's the oil pump?

 

No, oil pumps rarely go bad, and they will not make more pressure when they do go bad. Replace the sending unit if you're worried about it, cheap and easy to do. The oil pump does not make oil pressure, it only makes the oil flow through the system. The thight clearences within the bearings at the rods, crank, and cam make the pressure. You never see a pump rated for pressure, it is only rated for flow.