Looking for some experienced pointers.

Running 1995 LT1 Z28 M6
383 LT1 Hi compression 11.5:1
223/231 .610/.594 112 LSA cam
AFR 210 heads. Comp Ported. 2.08i 1.6e

Car runs very well. The roads over here are just too short.
Idle is pretty sweet now.
Currently running SD Closed loop tune.

The problem is just between ... lifting off the clutch and giving it some juice, ie between 1000 - 1600 RPM
If i give it a little throttle and get up above 1500 rpm it's fine. It will just about take 6th gear at around 1500rpm.
If i'm sat in traffic and rolling about 5-10mph throttle closed, in gear, it'll start bucking slightly, increasing to violent.
If i nail it, it's fine, your above that range.

I've had the idle lowered at 850 but put it back up to 900 again which helps a little (masks the problem)
I've tried timing up & down 5-10 degrees and not seen any real difference.

I've been told to go closed loop & richen it up.

Looking for info & direction to try.


Thanks
Mitch