[s-cars] Really LOW Boost!

[Calvin & Diana Craig]

OK guys, here's the problem.  I normally get about 15-20 psi depending upon
the usual stuff, rpm, weather, load, etc.  Today I was getting this "normal"
boost one second and the next time I stepped on it I got 4-5 psi, even too
low for just wastegate spring level of boost.  All of a sudden.  No other
symptoms...no missing, etc.  Revs smoothly to 7k rpms.

I checked the hoses, lower intercooler hose was just recently
replaced...they look fine.  On top of that I don't hear any of the
horrendous whoosh noises that usually accompany leaky hoses.

Swapped bypass valves with my '91 200...no difference.

I examined the wastegate diaphragm and it looked OK.

I removed the hose to the lower chamber of the wastegate which should cause
boost to scream up until the fuel pump cutout, but no luck, it did make it
up to 8-9 psi, though.

This is obviously not computer related since all that was knocked out of the
running with the last test I did.

Are damaged turbos that all of a sudden lose 15psi of capability still
capable of producing 8-9 psi?

I am really struggling with this one.

Thanks for any help!

--Calvin