Diesel Engine won't turn off

[stockmanreef]

Sorry if this has been posted before, but I could not figure out how to search this problem easily.

I have a 1991 300DT and the car will not turn off when the key is turned to the off position. I have to pop the hood and kill the engine with the Kill Switch. I know why it would not turn off initially, I broken the small line leading into the main vacuum line. Actually I broke the main line and the small line--glued both as a temp fix and everything was fine. The problem cropped up again, so I thought that my fix had gone bad. I replaced the broken line with a new one and still the car won't turn off.

I understand that there is a valve that comes off the IP that the vacuum accuates and that this could have gone bad--the car does have 330k on it. Is this the only other reason the car won't shut off?

How hard is it to replace this piece?

My other option is to purchase a normally open solenoid and put it in the fuel line leading up to the IP. Then I can just hit the switch to closed the solenoid and the engine will stop.

Thanks for the help.

ken