That darn vacuum system w123

[MTNdiesel]

I have an '85 300D turbo, and I've been slowly trying to find the vacuum leaks on it. I believe I have all the ones under the hood and am now about to go through the interior's locking system. But I drive the car regularly and use the engine shutoff lever. First is this bad to do? Second on some longer drivers it will shut off with the key. On about half of my short drivers especially if I'm just pulling it into the garage to put it on jacks it won't shut off with the shutoff lever. What happens is that it struggles to keep going and the air intake filter housing shakes like crazy as I hold the level down. I figured out that if I use the linkage to rev the engine a few times the the shutoff lever works but after the engine stops I usually hear the turbocharger making a "power down" noise. Any advice?

Also, can Dexron 3 or 4 AT fluid be used instead of Dexron 2. The manual says Dexron 2 but nobody really carries that anymore. Thanks