I believe the vehicle came with a silver colored rack dampener bolt. The replacement is gold. I had a silver original and had tried to get the spring loaded pin to work. When I finally got around to picking up a gold replacement I found that I was able to get the idle to adjust. I noticed the replacement pin had a much stiffer spring than the old one.
The MB shop told me he was surprised that any of these were still out there with the old silver rack dampener bolt in them. They had more or less all been defective. Once replaced the idle improved substantially. I don't know if that would made the engine cranky at take off though. That sounds more like a motor mount problem.