Throttle linkage looks very loose, and I lack power
 

I recently purchased an 84 300D Turbo Diesel. It lacked power, but I am alright with that, assuming that I can fix it. I think I nailed my problem. When I hit the pedal, the engine doesn't seem to go to full throttle. So I checked the banjo bolt and other probably causes, didn't seen supect. However, the car does not turn off when I kill the key. A bad fuel injector shutoff solenoid. It's not a runaway diesel, it just keeps idling. So to turn off the car, I have to pop the hood and hit the 'stop' lever to kill the engine. After doing this a few times(with varied results- sometimes I had to almost jam it down and wait for the engine to sputter and die), I noticed that the entire linkage seemed a lot looser than I thought it should. I checked a few things, then noticed that where the linkage comes through the firewall up near the windshield, the seal, bearing, or whatever it is, seems to be falling apart and disintegrating completely.

Can anyone tell me if that makes sense to be my problem? Is there anything else with the linkage that is a common failiure point? Do you think that fixing this will fix the problem? Is there a DIY for throttle adjustment anywhere? Thanks!

I know my linkage is kind of loose. The first 2 months that I owned my car, I thought MY throttle problem was because of that. However, one day after vacuuming my interior, I forgot to replace my drivers side fllor mat. It was like driving a new car. The pedal was nice and easy to push (but still plenty of resistance). Turns out the floor mat had been coming between the pedal and the kickdown switch. This caused me to look nearly an inch pedal action. You may want to try that.

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.

Sounds great. I'm rather intimidated by all the vac lines I see in there though. Do you know of a DIY for this? Thanks!

DIY Repairs
 

Check out www.dieselgiant.com for step-by-step instructions on how to diagnose and fix many problems like this. I remember one of the DIY articles talked about linkage problems (I think it may be under the valve adjustment section) and another talked about the banjo bolt (under the ALDA discussion).

Good luck!

Yep, Diesel Giant is neat.
I wasn't able to find Diesel Purge at my local auto store, and I don't want to order it- does anyone know of a chain that carries it?