I had a similar issue, turned out to be a hair line crack on the porcelain of #8 plug. Also I had an issue with my 2 step button getting stuck. Just throwing ideas out there.

 

What wideband are you using ? Sounds like your running to rich and maybe your wideband will not register anything lower then 11? I know mine stops at 10.0 but I would have simlar issues when the tune would hit 10.5 afr or lower
Change the plugs and lean it out to 11.5 and see what's good
Also log your runs so we can look at them

 

If it's breaking up just starting to tip into boost and your a/f is even on the chart (10.0+) it's most certainly spark related.

 

Update:

Put in the NGK BR7EF's, and the car runs noticeably better, albeit still has a stutter.

So I got to looking through one of my logs that I made a full rpm pass through. The AFR error was a .99% all the way up. I found this obviously to be strange so I looked at the raw AFR numbers. 10.93 all the way up.

So I looked at my formula and found at least a major part of my problem. The ground offset formula for my wideband (I use an excel spreadsheet) had the equation as volts/.625+10.093 and somehow I copied that over as +10.93. So the absolute lowest afr it could register was 10.93 (which is actually 10:1) and also happens to be where I am the whole time I am boosting (somewhere below 10:1 afr).

Needless to say I need to get the formula corrected and lean it WAY out. Just hoping I didn't kill these new plugs as I drove it about 40 miles last night at what I thought was ~13.5:1 afr (which was actually .9 points lower).

So I assume a sub 10:1 afr could cause a distinct stutter/hesitation?

 

Most defiantly.

 

Anything below about 10.5 on gas can start really misfiring.

 

This is were HP TUNERS pro makes life easy. No math needed for wide bands. all ready set up for you.glad you found the issue. Keep us updated