Great site, and I hope someone out there has an answer to my
mysterious problem.

I have an 86 300E, 5 speed manual (145K miles) that now refuses to start or
when it does it runs very rough. Another symptom has been that when it sits unstarted for a week or so
it would start, run rough, quit after a few minutes then after it sat for
a few hours start up and run fine. The last time it sat for a week it just
refused to start and is now at the mechanics. It has been at my mechanics
for a month and he has tried:
new plugs,
check the fuel pressure, says it is good,
checked both the fuel pump and overload relays
tried a new control unit from another 300E along with a few "rebuilt" ones.

Nothing seems to fix it.

My other ideas are: O2 sensor, and wiring harness. Mechanic thinks there
is a timing problem but I am not so sure given previous history above before
the latest problem.

Help!!