What would cause my oil pressure to go up and down?

It's normal for your oil pressure to be lower when stopped. Check your car specs for values. But typically the range would be 40-60. Also oil pressure sensor wear out with time, so either test it's volt or resistance values or install a new one.

Sorry about that I was thinking of the V8. The I6 (on further review) should be at stop/curb idle: 13 psi minimum @1600 rpm & above: 37-75 psi. Higher or lower you would want to check your oil and coolant level. Being low on coolant (once engine warmed) will effect oil pressure. Form what I understand 89-90 I6 Cherokees at oil pump problems at 140-150k miles. Though you have a Grand so it wouldn't apply.

It does have almost 300k miles on it. Could the oil pump be going bad? It started doing it alittle over a month ago.

Yes with that many miles, I would definitely replace the oil pump. Because if that goes out you'll have a seized engine in no time. If you want to take it a step further, replace your con-rod bearings and piston rings or just run a thicker rated oil.

when i keep on the gas the oil pressure stays on 30 but when i come to a complete stop it drops to the 2nd white mark by the red line it stays there intell i get going again how do i stop that from happening

are you using 10w30 oil? This is what ALL 4.0 engines should use.

Driving home from work today my 2003 Cherokee Check Engine Light went on and the gauge is pointed on low exactly. I called my father and he started freaking out because he said my engine might blow, over heat. Is something wrong with my engine or is my gauge bad? Mine is not going up and down after i start it or am not driving. Mine is at the low gauge level at all times with check engine light. any kind of input would be awesome

My car Jeep 2011 chrokee ever time my tire pressure up and diwan