Mid rev stumble

[Dave Head <dhead@sundial.sundial.net>]

I still have a mid rev stumble - prior to full boost. Once the car 'clears
its throat', it pulls strongly without any problem. From just above
'lugging' speed in 2nd today I heard a minor backfire/popback during the
stumbling. If I back off slightly it will disappear. If I accelerate slower
it won't occur.

Car: 89 200q w/184K and Tap chip.

Items replaced/checked thus far:
both wastegate control hoses
O2 sensor
fuel filter 
complete 'large hose' crank vent unit to the intake boot including the
triple connector at the valve cover.
WOT switch assembly
new plugs
200 miles into a can of Techron to a full tank of 93 octane.
idle vacuum: 14" (well above the idle vac of my 87 tq, which is 15-16".
ISV cleaned

Any ideas?
********************************AUDI FAN*********************************
                EMCM(SW) - retirement 30 Apr... Dave Head  
87 5KCStq 249K miles - fer sale, durned good price
89 200q 184K miles - cleanup in progress
    qcusa #3442                                           Oviedo, Florida  
If my email bounces, use dave.head@pyxiscorp.com   
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