Hello Folks,
I'm after some advice if possible.

I have just replaced the headgasket on my trusty W126 300sel. It runs very well, very quiet, however when at idle and in drive, it is rather lumpy, as if it's misfiring but isn't.

I have replaced....

Headgasket,
Exhaust, inlet gaskets,
All oil seals,
Spark Plugs,
Distributor Cap,
Rotor Arm.

I've checked the leads as well, they are fine.

Must admit, I'm a bit at a loss now, unless it's the idle control valve that needs clearing out, but it was fine before I took the engine apart. The engine and drive are fine other than this....

However, Could it be one of the multitude of vacuum pipes that I took off and have re connected . Stupidly I didn't take a note of where they went. Doh....

All help gratefully received folks,
Mike.