If there was an EGR valve used on that engine, you'll see it shown on the emissions sticker under the hood. It will have a black plastic disc on top of it with a vacuum hose and a two-wire connector.
Excessive pressure in the valve cover is caused by blowby past the piston rings. A cylinder leakage test will confirm that. A compression test will show if the compression is low. A cylinder leakage test will show why it's low. Many auto parts stores that rent or borrow tools will have a cylinder leakage tester. You need compressed air to run it.
There was a common problem in the '90s with the oil pressure sending units reading low intermittently when they got warm. Use a mechanical oil pressure gauge to see exactly what the pressure is. If it starts to go down, the oil pump pickup screen could be clogged or the oil is the wrong viscosity. Use a thicker oil at the next oil change. It's unlikely the bearings are worn because the pressure would have been low after idling for two hours.
Saturday, December 28th, 2013 AT 10:27 AM