99 ranger oil gauge

I have a 99 Ford Ranger with 145K miles. Recently, the oil gauge started jumping around at times. It seems to happen when I slow down and the RPM’s drop and the needle will drop to the bottom for a second or two then bounce back up to a normal position. The oil level is good and I don’t hear any noise like the oil pump or anything. What do you think is the problem?

Try replacing the oil pressure sending unit next to the oil filter.