P.E.H: Like I said, I drove a 76 300D for a while, and I thought that the 240D had the same setup. Obviously I was wrong. I knew that the black knob adjusted the idle, but I was unclear how. I stated that in my post. As far as depressing the accelerator goes, I was following instructions given in the manuals of the 76 300D and my 81 300SD. I did not intend to give bad advice, I was trying to be of assistance. It is clear that I was not. I apologize, and will refrain from doing so in the future.
1976 300D (W115) - 330K and still going (sort of)
1991 300D 2.5 Turbo - Sold at 221K
1983 280SEL - Sold at 206K
1981 300SD - Sold at 232K