I've got an issue with the 380 where occasionally, especially when cold.
She runs very rough.
This causes surges in the car through the transmission.
And on occasion causing the brakes to feel soft, even after driving a while, and it seems to be running smooth.

I've had the vacuum hose off between the manifold and the booster.
It seems to work OK, I can suck through the booster end, and by holding my tongue there, the vacuum valve holds negative pressure there and seems OK and that end.

Blowing from the manifold end, causes it seal, but sucking through the manifold end, i.e. normal operation, it sometimes seems a bit hesitant.

Is it possible this needs replacing..

I have a persistant code problems which throw a CEL
P0106 - Powertrain
Manifold absolute pressure/Barometric circuit range/performance Problem
P0101 - Powertrain
Mass or Volume air flow circuit range/ Performance problem

I've cleaned the Air sensor.
I've disconnect the battery as well.

No matter what I try, the problem always returns with a week or so.

Anyone heard of these types of issues before?

I don't even wether the two problems are related, or if its something else causing the vacuum leak, and the poor brake is just a result of the low manifold pressure.

That hose should only suck air to the point where there is vacuum in the brake booster. Of course, if the brake booster diaphragm is leaking or ruptured, the intake manifold will keep sucking and make the engine run lean.

The manual shows how to check if the brake booster is holding vacuum.
Engine off, press brake down a few times to reduce vacuum (if any)
Pedal should be high and hard.
Keep foot on pedal, start engine. Pedal should sink noticeably.
Switch off engine. Pedal should stay down. If you release and press the pedal a few times, the takeup point should come up a bit each press.

Check the hose itself for holes and cracks. The valve itself rarely stuffs up. (generally)

http://file.autopartoo.com/productimages/2011/12/13/34461.jpg

Check the seal at the valve, top of picture.

Passed that test no worries.
And the house was/is in good condition.
So perhaps it's just an anomaly cause by the manifold leak.