Hello, I recently had my 1974 450sl worked on at a local
shop. The problem was that the idle was way too high.
After getting the car back, the idle was where it should
be, but no there is no acceleration at all. Any ideas as
to what is wrong? Thanks for any help you can give.

 

Possibly they just retarded the timing? Is it harder to start?

 

It seems to me that the fellows who worked on your car did a less than adequate job and should be held responsible. Return the car to them and suggect thatthey resolve the problem or refund your money.

 

Check out that the mechanic didn't knock off a vacuum line while messing around with the idle adj. There are many lines in that area.