Gotta be a worn pivot then. If it goes off center under vacuum, it' won't move easily since it will be jamed up on the sides of the venturi.

Also check to make sure you aren't dragging the cruise control servo for some reason -- I've seen some pretty strange configurations of throttle linkage when someone didn't know what they were doing when they put it together!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!