Hesitation around 4k!

[fast400]

I'm getting some momentary hesitation on WOT runs right around 4k. It's smooth up to that point, then I get one to two hesitations before it pulls through. I'm at 820mV and 0.0-0.5 KR; MAF going all the way to 255 no problem, INT 128, BL 124. I do get tiny little carbon specks on the rear bumper (still too rich?)
The car is stock except for TT chip and a 160 thermostat (It'll also still get up to 200+ in traffic in 80F weather???), 30lb Tomco injectors.
It's really annoying to have the loss of accelaration at the upper part of the run like that. I notice it mostly in 3rd also.
Anyone run into a similar hesitation?

 

[turbows6]

never had that problem, but it sounds like it's likely related to a fuel issue. In my experience ignition problems just get worse as boost and rpms go up, but it sounds like your 02's are pretty close to correct. That sounds like a pretty hard one to diagnose. I would just look for any odd readings on your data logger. Throttle position sensor etc...