W123 Oil Pressure Drop

[Dale240D]

Just nursed my 83 240D home. I was driving from gainesville,fl to starke to see Blackfoot in concert!! 10 minutes outside of town i notice my oil pressure gauge dipping. I've never seen it below 2 while at speed. I was going about 45 mph. Terrified, i pull over to turn around and head home. It continues to drop to a little below 1. I pull into a parking lot and as it's idling , the pressure goes back up!!! It stays up as long as I don't go above 35mph. at idle, it's pegged. At about 30-35mph it's around 2, Above 35mph it drops off quickly. I had just topped the oil off right before starting out on the trip. 2 weeks ago a compression test came back 300,300,400, 300. I have about 190k miles on her. I've NEVER had this car give me oil pressure problems. Also my understanding was that as a pump started to go bad, it was at low rpm when you would notice it first. Any clues, comments or suggestions gentlemen?(and ladies if there are any out there!)

Dale