Just a thought Patsy, but did you attempt to adjust the idle with the throttle linkage disconnected? I was thinking about this, and you recently replaced the leaky hand pump, perhaps the PO, attempted to overcome fuel starvation by tightening the linkage to increase idle speed.
Just a guess.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.