Bad OVP, going bad over time and the fuel computer continually adjusts to keep the car running. Until the old OVP is completely shot (although I do understand electronics tend to go out at once).

Now pop in a new OVP, the fuel computer has memory, trying to feed input according to the memory of the bad OVP resulting in running worse with the new OVP installed. Needs time to reset the memory.

Best guess.

__________________
Mike Tangas
'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.