560 SEL Loss of Power
 

Hi, I am new to this forum and I love all the honest info for fellow Mercedes owners. I have really enjoyed many of the posts, especially Mike and rebuilding a 560SEL. I hope someone can help me with my problem on my '89 560SEL.
Recently I lost power during acceleration, it is most noticeable when climbing a hill. It is fine for city driving and not noticeable at slower acceleration but when I "Get on it" it turns in to a dog. The odd thing is when I have the pedal to the floor and I lift up on the throttle the car slightly accelerates. I asked my local Benz Mech and he said that it is the Fuel Distribution Manifold. I looked the engine over and found a hose disconnected from the smog pump. Reconnected- No Change. Now I am suspecting the Fuel Pressure Regulator. It has a vacuum line coming in and when vacuum is applied I can hear an air leak. Is this normal? or should this be air tight? Any other suggestion?
Thanks in advance!