Bad sender... possibly an open in the circuit, bad cluster..... possibly no
oil pressure but I would expect the cam followers to let me know. Sender is
locate beside the oil filter on the 4.6.

All the same, I wouldn't drive it without knowing for sure if I have oil
pressure or not...

First order of business is to put a mechanical oil pressure gauge on that
engine and confirm if you do or do not have oil pressure.  If you don't have
any oil pressure DO NOT run the engine any more until repaired.

Fords "idiot" oil pressure gauges are poor at best, they are dampened so
nobody gets excited about normal pressure fluctuations, and they never show
an actual pressure value.  You can check the throw of the gauge by
unplugging the sending unit, and taking a jumper wire and grounding the lead
that plugs onto the oil pressure sending unit.  With that lead grounded your
gauge should show full/max scale.  If it doesn't work properly I suggest you
consider installing a real oil pressure gauge.

Good Luck

I can top that. My 2000 4.0 L oil gauge is pointing straight down. When
turned off the needle would rest on the needle stop. Well somehow it's
flipped around and is under that needle stop now. No Engine running points
straight down, when you start up it jumps up to peg at the needle stop, good
enough for me. There is good pressure but we've had problems with this idiot
oil pressure gauge (Replaced a stuck sendor year or so ago.)

G