Any thoughts on the following would be appreciated:

M5 sometimes runs great and at other times hesitates around 3500 rpm. Replaced: in tank pump, fuel/air filter, wires, plugs, adjusted valves, 02, and fiddled with the AFM by moving the pointer "down" the shaft slightly.

Symptoms occur when at speed (60+) when near full throttle is applied. It will either accelerate great and through the range, or hesitate and throw a puff of unburned gas out the tail pipe (I can see this in the rear view mirror under the right light conditions).
It might be pinging, but I am not 100% sure.

Without any research, I am thinking that perhaps the AFM is still not sending a clear signal and drops out causing the computer to cycle? Any thoughts... This is my daily driver and it is painful to baby it...
thanks again,
Dean M5 '88 ///M5
'95 RRC
'60 Healey BN7
'72 Kabota :)