Best way to check is to disconnect it from the fire wall and try the linkage from there out if it is easier check the accelerator to fire wall connection. Keep doing this until you find the part that sticks. Some benzes have a bushing on the firewall connection that can cause this. Good luck hope it helps.
m

__________________
Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)