Originally Posted by rhodes2010

Definitely replace the bushing on the firewall that holds the throttle linkage rod.
Do not do any adjusting until this is replaced.

Independant MB repair shops or the dealer has this item for a few bucks.

This is certainly a big problem. Easy to replace.

2nd - Engine shutting off with key.
Plenty of discussions here on this, you can search them out.
A lot of them recommend using a handheld vacuum pump
(mighty-vac, sears, harbor freight - under $30) to test the shutoff
on the Injection Pump (IP) and the feed line to the key switch,
and the line coming out of the key switch.
This is very easy to diagnose. You will be fixed in a few minutes.
There are only two vacuum lines to worry about.