88 5ktq poor running

[Fuzzzydog]

Hello once again fellow Audifans. I am having a bit of trouble with my avant
and want to throw it out there to see if anythings sticks with you.

vehicle is bone stock
I suspect the oil rings are well on their way to being shot as I get copious
amounts of blue smoke after idling down a hill in gear.  But now I wonder if
the oil isn't getting in some other way....

my problem appears to be fuel pump cutout under boost conditions - most
noticeable when engine is cold.  I can accelerate gently and speed will pick
up slowly but if I really get on the gas (not even to WOT) the car starts
bucking.  I am suspecting this is the fuel pump cut off, but this happens
even when the dash gauge only shows .9 to 1 bar.  Now here is an odd thing
on this - I hooked up a boost/vac gauge right at the ecu and went for a
drive - according to this gauge I am running at vacuum at all throttle
positions except almost wot and even then barely makes it to 5 PSI.
However, for the most part the car runs 'fine'. I can tell it doesn't have
the power it used to but it does run decent and I can easily keep 120kmh on
the highway.
yesterday I did a vac test on the upper wastegate cap and it did not hold
any pressure at all.  fortunately, I had 2 spare wastegates sitting on the
shelf (1 from an 84/85 5kt, and one from an 86 5ktq) and they both tested
good. now here is an interesting thing - I opened up the older one (84/85
can't recall) and the diaphragm was doubled up and it had a fairly long
spring with 3 green stripes on it.  when I opened up the defective wastegate
the spring had 2 blue stripes on it and was much shorter, and there was only
1 diaphragm.  meh- I closed up the good one and installed it anyway. test
drove and it seemed to run 'better' overall, but still cutout at high
throttle application and aux boost gauge still showed it running in vacuum.
this aftermarket boost gauge - the needle does go to 0 when the engine is
shut off.
Now a new problem though - when I went for my test drive, as I slowed to
make a turn to return home, let off the gas, clutch in and engine stopped.
coasted to the side and wouldn't restart. for years now, car has always
started fine. fiddled and hmmmed and hawed for about 10 minutes, tried again
and viola! it started.  just as I got home, same thing - clutch in, off the
gas and stalled. would not restart for a few minutes then started and idled
fine.
one other thing - the crankcase breather hose is collapsed - just noticed it
yesterday. dk if that matters but..... also when I was replacing the
wastegate there was a significant amount of oil in the lower wastegate
hose.  this I suspect is NOT good.

MFTS is fairly new but I am suspicous of it because the temp according to
the gauge is always coldish and I seem to recall in the past having probs
keeping it cool. the A/C on this car is removed so it does have good airflow
throught the rad. when I got home yesterday and it stalled I checked the
temps at various spots on the engine with a laser thermometer and nothing
was higher than 86 Celsius.

Checked the spark plugs and they were definitely more white than tan.  they
are the bosch platinum single electrodes.  I am going to replace with the 4
electrode ones that I always used to run without problems

So, with these hints and tips - any suggestions?
does anyone know of a timed relay that would prevent starting this vehicle
for a few minutes under certain conditions?

TIA