Very strange situation with this car and I'm having a hard time figuring it out. It's an 08 ZO6 w/ a solid roller 440 LSX, ETP LS7 heads, etc etc. Car and motor were built by very reliable sources, so it doesn't seem to be anything mechanical. I've just got this weird issue where it pulls clean all the way to 7000 the first pull you make after starting it up, but if you make a second pull, usually around 6800 I'm getting some sort of flutter. Almost like acceleration based limiting. I've tried changing the filter coefficients to minimize the effects, but I'm still getting the same issue. If you turn the car off and try again, the first pull is always clean, and the second pull always hits some sort of flutter around 6800.
I'm not really sure what it could be. They originally thought the car had valve float, but the valves have been ran correctly and everything seems to be in place mechanically.
Here's the current tune, and a data log of back to back runs. First run was clean to 7000, second run started to flutter and fell off on the dyno at 6800.
BTW. The car has FAST 60# injectors, haltech cold air, and American Racing 2" headers. it's a fairly large cam with 13:1 compression.