Have a 88 2.9 that has a bad habit of developing oil problems. From time to time it will suddenly start to labor, several seconds later the lifters start to rattling, then the oil light flashes. It will go away after being allowed to sit a day or so. The first time it happened the cause was thought to be too much oil. Drained a half quart, didn't have any more trouble for months. Currently it seems to have just the right amount.

 

Sounds like the oil pickup tube is tying to stop up on you or the oil pump is shot. Either way you have to pull the engine to fix the problem.While your at it put a good oil pressure guage in it if you dont have one already.JMO