If you had it set at 6 and it dropped when you got on it, the pump output is low. Either the pump is going south or there is a restriction in the suction side somewhere. Might be time to do as AJ said and do a pump output test.
I just dropped it off at the alignment shop, about a 20 minute drive
And it did fine (but the wife was behind me in the charger, so I didn't get on it since I didn't want to loose her)
I did get one more idea on the way over, so I'll check that out and I'll let allayall know