My gauge was doing the exact same thing as Howser mentioned. I noticed that the previous owner did his last oil change with 5W20. I decided to replace the oil with Castro High Mileage 10W30 with a Motorcraft oil filter. The "jittery" gauge issue went away for a few days, but now it is starting again. It happens sporadically and it is not as flickery as before.

The oil pressure switch has been replaced.

Does anyone have any other suggestions?

Thanks