1974 Mercedes 240D Runaway when Started

[CJW]

So I have been getting my 1974 240D going and a couple of weeks ago I changed all of the fluids and ran it every day in its parking spot for about a week. Ran beautifully. Then, I was busy for a week and was waiting on parts anyway so I did not mess with it. Started working on it today again and have this issue. As soon as it starts it revs up realllllyy high and smokes bad (just like a runaway) and I use the butterfly on the intake to slowly bring it down and then kill it. I spend hours trying to figure out what is going on but I can't. The throttle is completely at idle. The idle adjust knob by the key is all of the way down (it is running way above the high idle anyway). If I take the starter/shut off knob and push it back in (as if to shut the engine off) but not all of the way, I can bring it down to idle if I feather the knob. It almost seems as if the IP rack is stuck but I cannot tell. I know the 300D engines have an ALDA and people say you can look inside it but there is not such a thing on the 240D cars. Any help would be appreciated! Thank you!!!