Yes, there is adjustment!
Take off the panel underneath the steering wheel, so you can get to the pedals.
There you'll find a simple thumbscrew you can use to adjust the amount of slack - I did and now the lightest touch eases you forward.
Reading the latest 'Mercedes Enthusiast' magazine made me laugh - they run an '86 2.3-16, and on a trip to the Nordschleife had the throttle stick open at full! They sounded surprised, but I don't think many of the 190 owners here will be - it can happen if the linkage is allowed to dry up - so lubricate it while your there!
What bugs me is that the so called 'enthusiasts' called the RAC Roadside Assistance - surely any enthusiast can diagnose and fix a sticky cable..?
Then they ran off the track and hit a barrier (only minor damage though).. sigh...
btw where are you in England?
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black