1999 ML430 Transmission Question.

[1highhog]

Guys, I have a heck of a question about my 1999 ML430. The other day, while I was driving it, the engine light came on and I drove about 3 miles to my jobsite. That afternoon, or about 8 hours later, I go out and crank the car, the light is still on, but I decide to see if I can make it another few miles, about 5, to a transmission shop. The car never gets out of 1st gear, so I end up parking it and trailering it to the trans shop. They have had the car for about a week, they change the trans filter and fluid, and remark that there is hardly any metal shavings at all in the fluid, they try and diagnose it, it comes up code 715, which is a sensor A, speed control. They replace it, but still the problem remains. Today they give up and decide the best thing for me to do is take it elsewhere. This is not a Mercedes shop, just one of the better one's in town. My wife usually drives it, and she said that about a week before I drove it that day, it had started to act sluggish when she was leaving from a dead stop on an incline, but would do fine on a level surface. This is why the Transmission shop decided it might me the filter. Has anyone ever had this problem? I'm now going to take it to the Mercedes Dealership, but kind of hate to because they do not have a good record with the local Mercedes owners. Any help would be appreciated.