I have a fuel injected model. I have done the two bottles of Techron trick. Infact, I let it idle for 1/2 an hour then help it at 2500 for 5 minutes or so and let it idle for another 20 minutes.
The car loves to idle and idles very well.

For the vacuum leak, what am I looking for? I have checked pretty much everything in sight in the engine compartment and have replaced most of the vacuum lined (one by one). Is there a vacuum connection between the transmission and the intake?
Is there a line under the intake that I am just not seeing? is there a way to test the amount of vacuum and, if so, where is the best location to take the reading?

I have checked all of these suggestions before..except the valves being too tight. That is a new thought to look into. Does too tight mean not opening enough? I cannot make too many adjustments, as they are hydralically lifted.

PS: My wife has insisted that I sell the car and cut my losses in time and money. This is our first Benz, and if she wins this battle, our last. that really stinks for me because I want to get a 560SEL.