oil pressure skyrockets

my oil pressure sky rockets, way off the gague, all the way to the bottom. i searched a bit and turned up this thread.
http://www.naxja.org/forum/showthread.php?t=85004&highlight=high+oil+pressure
Since it only goes way up when i rev it, and then returns to normal when i am off the gas, i am fairly sure it is the oil pressure relife valve. ive got a couple of questions about this, how bad would it be to still drive it, or even go wheeling? i had a trip planned for friday to holister. Also, in order to replace the valve, i have to get a whole new pump correct?

Did you look at the sending unit?

my xj did the same but my sensor was not connected all the way. pulled it off completyl cleaned it up and put it back on and it was fine.