I was trying to find the answer to the following problem. I went on the internet and did a few searches, there were plenty of people with similar problems which they could not find the answer to. This is obviously because nobody took the time to come back and post their findings (gee..thanks for sharing). Since nobody helped me out, I thought I might help others with this frustrating and annoying problem. Keep in mind, this was MY problem, and may not be yours..but for the price below, give it a try. Oil sending unit. Low oil Pressure Problem. 1996 Jeep Grand Cherokee 4.0 150,000mi. The engine sounds and runs as if it has 30,000 miles on it…she’s is t-i-g-h-t. The problem was after driving for longer than about an hour, the oil pressure will drop to zero when coming to a stop. Like in city driving and coming to a light. Or HWY driving and getting off at an exit and coming to a stop or near stop. The oil pressure would suddenly drop from 30psi to zero. The check engine light would come on and a tone would sound. But anything over 2000rpm’s and it is fine. It reads 40+ lbs at 70mph or 2000rpm otherwise. I had this problem for several years, but it was rather intermittent, sometimes not happening for months. I would just shift into neutral and rev. the engine a bit, and up it would swing. I run 10/50w oil being in Florida. I tried switching to 10/30w, it “seemed” to get worse, and of course this was nothing I wanted to experiment with. This problem did not happened on short trips only on longer ones. But recently the problem became a little more frequent I had to investigate since this is a potentially SERIOUS problem. Possible problems were oil pump wear, crank bearings, cam shaft bearings, oil pressure valve and a couple others, but it only did it every now and then….the above would have happened quite a bit more frequently I’m sure. SOoooooo, I decided to inspect the oil pressure sending unit. This is located just above the oil filter, its round, plastic and silver, with two wires running into it, you can’t miss it. I unplugged the wires from it, and low and behold, there was oil there the male/female connectors came together..surely this can’t be right I thought. I shopped around, I got prices of $50.00 for the first two phone calls, and $30 on the 3rd call at AutoZone. Drove home (problem happened again), installed new sending unit in, drove around, noooooo problem !!! I decided to take a hacksaw to the old one to see if and how much oil was in the internal part of the sending unit chamber, or if there was supposed to be any there. I started cutting like a bologna slicer, it was filled with oil. I finally cut right where the plastic and metal join. BINGO, there was a plastic/neoprene gasket in there that is MEANT to separate the oil from the electronic parts. You see, oil is force in the small hole, and then this membrane is supposed to flex and press on the electronic portion giving a reading. The neoprene gasket was leaking!! Problem solved. Ready for another 100k I’ll bet. I had the same problem with mine, first there was an oil leak and it would jerk slightly from between 1500 rpm to 2000 rpm so we taught that this is causing the jeep to jerk so we had that fixed. While the jeep was getting fixed i read this suggestion so i told the shop to check on the oil pressure switch also. The mechanic said he did checked it and every thing looks good. The jeep worked pretty good for a day no more leaks then it stats jerking again the next day. So i decided to bring to another shop and have them diagnose the jeep and found out the the motor mount has gone bad so that was the main problem. Hope this will help you.