Oil Pressure Gauge

[jlongoria]

I have a 2004 Ford Explorer with 155k miles on it. I have replaced so many things on this truck, I am trying to not get discouraged and sell it. Its in great condition and runs smoothly. The problem I am having is the oil pressure gauge, when I idle at a stop light or stop sign my oil pressure gauge reads 0 but once I rev the engine or take off the gauge goes back to its normal reading. I have already replaced the oil pressure sensor 3 times just to make sure I didn't buy a faulty one, I bought the regular on, then upped it and got the more expensive one, and lastly went and just got it directly from the dealer. Still oil pressure goes down at idle, I took it back to my mechanic and he said it could be the oil pump. I took it back to him got it replaced and still when I idle no oil pressure. I had a few oil leaks but I had them fixed a couple months ago while replacing the transmission. I have to add that it doesn't automatically start happening once I start driving. I have to be driving for at least 30 minutes or so. I don't know what it could be. I can tell my mechanic is even kind of agitated with this damn gauge. I'm taking it back to him so he can run it with a manual gauge to see if that tells him anything. If not any suggestions on what it could be or anyone with this problem that has gotten it fixed? If all else fails I have no choice but to sell this truck. I have put more money into this motor than what I'll ever get back if I sell it, I just need it to run to get me to school and work please help.