About a month ago, the gas pedal broke on my 300sd, it was rather scary because it was hard to press at first, then the pedal broke loose and jammed the throttle wide open, and if I hadnt been able to shut it off with the key (which occasionally happens, but not enough to be able to find something wrong and fix it), it probably would have ruined the engine before i could unstick the gas pedal and shut it off. After looking how the gas pedal is designed, i cant believe that mercedes would have chosen to use a part with a design that is so cheap and dangerously stupid on a car that is otherwise so well designed.
I went and bought a new gas pedal at the dealer, and the part that attaches to the gas pedal rod is completely different (although the part number hasnt changed), and while it probably wont break in the same way the old one did, it doesnt fit easily, and it wont always return all the way unless i put my foot under it and pull it back up. I dont think the problem lies elsewhere, becasue after the original gas pedal broke i got a used one from pick and pull to use until i got a new one but it didnt stick. I didnt feel comfortable keeping it on there because it was just as old as the one that broke, so i didnt really trust it. Im not sure what to do, I have a choice of driving the car with a sticky throttle, which makes me uncomfortable driving on the freeway, or getting another used gas pedal of the old design, and risking having the engine run away anytime i step on the gas pedal. This seems like such a simple problem, but it is making me not really feel comfortable driving the car anymore. Does anyone have any suggestions?

Go back to dealer and make them install it. Shouldn't take them more than 10 mins.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 102k - mine - (OC-104,600)
'17 Metris(VITO!) - 26k - wifes (OC-25k)
'09 Sprinter 3500 Winnebago View - 57k (OC - 63k)
'13 ML350 Bluetec - 73k - dad's (OC-75k)
'01 SL500 - 92k(km) - dad's (OC-94,000km)
'16 E400 4matic Sedan - 122k - Brothers (OC-125k)

I picked up several while at the yard. They ended up being free. It is a common part and those from at least to 89 fit my 85SD.
by the time you deal with the dealer, you could fnd some at the yard unless you are in the frozen, rusty north.

Other models from that ere fay fit also ie 123, wagon etc. The filler on my floor came off but I was able to make a connector with plywood and a piece of metal from a tin roof that I had lying around.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. Probably up for sale in the fall 2020 still have it. 85TD beginning to repair to DD status. Waiting on shop to do minor but more than I can do rust.