Missing Boost, back again!

[Trevor Topley]

I'm happy again,
                        nobody came up with a reason for my 200q having
lost its 2bar boost 3 times now. A couple of nights ago I added a 1/4
turn to the controller, but as expected it made no difference, 1.7
reached easily, dropping off to 1.5 in 3rd at 5000rpm.
Then coming home from work on snow covered roads, with summer wheels
still on, suddenly realized it was all back again and more(+ 1/4turn) as
we started to break the tires all loose and start sliding sideways!
I'm glad it's back again, but what the heck is going on??
I've ruled out a leak, as it cannot come and go like this.
Had considered the turbo dragging or something, but each time it has
been exactly the same symptoms, with nothing in between.
Still looking for ideas, surely I'm not the 1st with this,
        in anticipation, while enjoying 2.0+ again
                                                                Trevor
Topley 90 200q