I've had some closed throttle decel surging issues for a while now and I've finally caught it with Datamaster and now I need some help figuring out what's going on and how to fix it.

Background:
Car is a '95 Z28 M6, stock LT1 casting ported heads, LPE 211/219 cam, 1.6RRs giving me .533i/.560e lift, HookerLTs, new O2 sensors, Meziere water pump, Comp R lifters, Crane double roller timing set, !EGR, !air, stock unmolested MAF, stock program other than cooler fan settings and disabling EGR codes.

This problem arose before the recently installed heads, BTW.

I decellerated from 72mph to 0mph in neutral, closed throttle. RPM range was 1650 down to 800. During this time the rpms would surge up and down. This fluctuation is in sync with a fluctuation between BLM Cells 17 and 18. BLMs for Cell 17 are in the 108 area (INTs go as low as 114) while BLMs for Cell 18 are in the 125 area (INTs in the 133 area). IAC counts were fairly
steady at 67 during this time. The O2's are in sync with this...while in Cell 18 the O2s will start heading "up the slope" to being richer, the MAP will drop as the rpms increase, I'll drop into Cell 17, O2s will peak on their cycle, rpms will start decreasing, increasing the MAP, and I'm back in Cell 18 for a repeat of the cycle.

I was told in the past to adjust my throttle blades open a bit more but didn't really get a good explanation for why. TPS voltage at idle is .55v and IAC counts at idle are 30. Are the 108 BLMs in Cell 17 the root of my problem?

I've got .uni and/or .csv files if anyone is interested (14k records total though).

Thanks,
Rob
95Z28