Lynn, what a horrible ordeal. I cerainly would be going nuts too. But as I look at this, you bought the car because you obviously found something intriguing about it. You seem to be an intelligent and savvy person therefore you knew up front there would be costs, albeit not the kind you have suffered.
Still throughout all this, it appears that you have had only one problem with it; the power jumps and missing. The way it rocks at idle is likely due to idle too low which probably is due to the cylinders not all firing. I had the same problem with my 74 450sl. All it took to fix was a minor electrical connection which was loose and cost nothing to fix. Otherwise it is mechanically excellent. It does leak (not burn) oil but I can expect that after 29 years.
It appears that it is not the car but the failure to repair it. You spent a lot of money but it was totally unnecessary as none of it worked. Everybody, but you, came out ahead.
My point is that your rightfully p.o.'d because of the money wasted but neither Mercedes nor the car did that, it was the mechanics experimenting on your car. If you would rather spend $50K for another car instead of $100 to tow it to someone reliable, that's entirely up to you. I admit that I would probably do the same.