Last Fall while winterizing the 84' 928S I noted a hissing sound from the bottom of the air intake nearest the windshield on the driver side, when I removed that air intake the gasket was incomplete (where the misssing piece went to??) and pulled all 4 intakes onthat side and replaced all 4 gaskets.
To access one of the bolts I loosened and rotated the distributor (after marking its' postion) and returned it to its' former positon after installing the air intakes.
Having installed and returned everything to original position I started the engine which started normally but now getting a rough idling engine, readjusting the distributor in several steps made some inprovement but idle is still sloppy. I don't have a timing light but if that is the next step we'll just get one. Other ? - is it wise/unwise to make adjustments to the distributor while engine is running

 

That's the typical way to adjust engine timing when using a strobe light.

 

Do you have to have a 'Ruf' Porsche to get a ruff idle??
jp 83 Euro S AT 49k

 

Yes, I'd say that is ruffly correct.