1991 Fox

[1SICDSG]

I have a 91 Fox and everything is running pretty good then about fifteen mins down the road the oil pressure gauge drops to nothing and when I come to a stop it sounds like something is loose clunking on the passenger side of the car in gear out of gear clutch in clutch out makes no difference I'm sure it has oil pressure if it didn't it would be going crazy and I can drive it for thirty forty mins and no change in sound of the motor only when it stops at a stop light it idles down and then clunk clunk clunk its driving me crazy any ideas would be greatly appreciated I am extremely new to this as well as I am trying to learn as much as I can as quickly as I can thanks in advance Jason