4000rpm hesistation

[Joan Kotjarapoglus <jkot+@pitt.edu>]

I recently had a chip and wastegate spring installed bumping the boost
from 1.2 to 1.8 bar on my 1987 5000 turbo quattro.  It has run
perfectly without a problem for over a month.  This past weekend 
after accellerating briskly in first gear at an intersection, it 
seemed or sounded like I heard soundthing odd, or it could have
been my imagination.  What I did notice, however, was the boost
was not getting past 1.2., and the emgome rpm seems to top out
at 4000 then begins to have hesistation stutter like the fuel
cutoff at the the rpm redline.  It I push it smooths out a touch 
and get slight past 4000rpm, and maybe to 1.3 or 1.4 bar but it aint
running right,  Friend tells me to check the intercooler hose for a
leak?  Any other suggestions for the source of this problem while I
have my nose underthe hood.  If I did not try to get past 4000rpm,
could not tell anything is wrong.  Run perfectly but for this
happening.     help    George K  jkot@pitt.edu