This seams like a very popular thing with these cars. I replaced the pump and the sending unit and my gauge still acts retarded. I think it's in the wiring on my car. Like previously said it is just a 6 psi warning light. If above 6 the gauge reads normal if below 6 the gauge will drop off.
94 GT FRPP: oil pump, driveshaft, pickup tube, timing chain and sprockets, rockers, lifters, pushrods, balancer, all new gaskets (except rear main winter project) . Heads have been milled and freshened up. With most the nick nack stuff out of the way soon I can really start building her up.