You already found and ignored the problem : the IP isn't reaching full throttle, this is a very serious issue and why I was able to buy my cherry '82 240D for $1,000 in the middle of the Diesel Mercedes craze some years back ~ it barley went 60 MPH on the flat freeway and couldn't go up any hills except in second gear (automatic) with the throttle pinned .

First, disconnect the _vertical_ throttle rod at the IP and figure out if the IP has some binding issue or not, then go through the various pivots and firewall bell cranks etc. and clean and lubricate each one, a little bit of slop anywhere in the throttle linkage results in lack of power and lower top speeds .

Yours sounds like totally screwed up linkages .

A 240D isn't fast but it shouldn't be sluggish either .

It should drive sprightly .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better