Hello, I am brand new to this site and to Mercedes. I have always wanted one so I finally bought a 1991 Mercedes 560 Sel. I bought the car as is. It has nearly 200K miles on it but the car is in great overall condition. The problem I have is that when you crank it up it runs smooth just for a little while then starts to die down, then pick back up, and repeat. You can drive it and it will go like nothing is wrong and then you can feel it missing again, then smooth again...you get the picture. I am a very good mechanic and troubleshooter but I have never messed with a mercedes. I am thinking fuel pressure problem but I have not even begun to diagnose...
If anyone has any suggestions on where I should begin to look please let me know...

Thanks in advance.

Darrell

 

Ok, so far I have changed the spark plugs, wires, and checked for obvious vacuum leaks. Car does seem to run better but it still lacks power and still stumbles down and back up when idling, and you can also feel it missing when you give it gas. My next task is to check the inlet screens on the fuel distributor and perform a fuel pressure check. I will post again once that has been done.

Any other suggestions?

Thanks