High boost cutout (sound familiar?) (mind help'n?)

[Bullyhart@aol.com]

List,
After messing with the Accel coil then returning the ignition to stock, I have
a problem at boost.  The truck stumbles and "flutters" at 13 plus pounds of
boost.  Otherwise it runs great.  I have replaced the plugs, wires cap and
rotor and even used the coil off of the Ty, to no avail.   I have looked for
vacuum line leaks and the like.  I have swapped out the boost control solenoid
and redone the boost control vacuum harness.
I'm running 40 psi of fuel.  Could a bad O2 sensor be naughty without tripping
a code?
Would you mind pointing me in the right direction?  I am considering swapping
the motor for something a little more simple.  Does Briggs and Stratton make a
V-6 mower?
Thanks for your help.
Daron
'92 Ty (runs good 'cause I don't dork with it)
'91 Sy (dorked with)
Dayton