Ok, I have an 87 300SDL. I am having problems with acceleration. If I stand on it it spins up to 4500 rpm (with 14lbs boost from turbo, so it is working), but no power. It dogs going up hills and don't try to beat a yellow light. Since there is air I am thinking it is a fuel problem. It sometimes is missing and runs rough at idle. Any suggestions?

 

Consider changing the fuel and air filters as well as putting some sort of fuel injection cleaner through the car.

 

ChecK your transmission Fluid level.
Also check the vaccum line going to the transmission modulator.
To avoid future problems check all vaccum hoses.