I have a 1992 W124 300D with the 2.5l turbo diesel engine. I have noticed that after 10-15 minutes of driving the car, the turbo fails to spool. After this time, I can no longer hear the turbo and there's a decrease in acceleration and power. If I turn off the car and turn it back on, the turbo works again for another 10 minutes or so. The car was just repaired because there wasn't sufficient vacuum pressure and the transmission wasn't shifting, the invoice states that the vacuum regulator and modulator were replaced.

I looked under the hood and noticed that a vacuum line from the intake sensor was unplugged (I'll include a photo)

I've searched quite a bit and I haven't really found anything documenting my issue.

I would appreciate your input, thanks!