Chris:

300K on the motor.....

Time for some work I suspect.

Not sure if the cam end rides in a journal type bearing? If so, some basic head work and a new cam might do the trick.

I think I'd give up on the fix it over and over thing and pull the head, then find a good machine shop and let them go over it.

My 2 cents.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"