Yes, 1989 and up Fords use an oil pressure switch, on/off, 5psi is the cut off
Could be a clogged passage at the switch
Disable spark, unplug both coil packs
Remove switch
crank engine over, oil will come out of the passage and any clogs
Clean it up, lol
DO NOT put tape on the switch threads, the threads need to be grounded to the engine for the switch to work
Install switch and see if gauge is still erratic
The switch is the Ground for the oil pressure gauge, with no ground gauge reads 0 with ground gauge reads 1/3 to 1/2 it varies by VOLTAGE not oil pressure, so the ground is important
If oil pressure was actually dropping under 4psi then valve train would start to make "ticking" noises, so if you haven't heard that then the bouncing needle is not a true reflection of oil pressure
You can add a "real" oil pressure gauge by adding a variable oil pressure sender in place of the switch and a gauge
If you want both the dash gauge and the "real" gauge then you will need a setup like this:
https://www.explorerforum.com/forums/attachments/parts-jpg.83284/
A "T" coming out of the current oil switch location
The larger unit is called a PS60 oil pressure sender, and works with most 3rd party electric oil pressure gauges
Or you can use a fluid oil pressure gauge and run an oil tube into the cab to the fluid pressure gauge
If you don't want the dash oil gauge to work then no "T" is needed, just install what you need for the type of gauge you chose to use
General rule of thumb for WARM oil pressure is 10psi per 1,000rpms
So at 700rpm idle 7psi would be expected, cold oil would be above 10psi most likely
40psi at 4,000rpm
Usual cut off point is 40-50psi at high RPMs, the pressure relief valve on oil pump starts to open to prevent too much pressure
Oil pressure is like human blood pressure, too low and too high is bad, lol
Oil pressure is the oil the engine CAN NOT USE at that moment
The oil pump creates the flow of oil thru the filter and then out to the oil passages in the engine
The oil that CAN NOT BE USED backs up in the main oil passage and creates the "oil pressure" you see
As RPMs go up the oil pump flow increases, but the bearings and valve train flow doesn't change much, gaps and holes are still the same size, lol
So oil pressure goes up with RPMs because flow IN increases but flow OUT doesn't change that much
You want pressure above 5psi because of gravity, lower pressure won't push the oil up into the valve train fast enough
And you want pressure below 70psi or the oil will squirt out too fast causing bearing washout, causes "dry spots" on bearings so they overheat