[74carrera911]

I have been in process of restoring my early production 74 US Carrera (#57) and have had it running now. Part of the restoration was going through the entire fuel and ignition system either cleaning or replacing components that I deemed were not working properly.
I continue to have an annoying problem with engine bucking/jerking in the 2000 to 3000 RPM range. This bucking occurs at light throttle and in all gears except 5th which is probably due to the higher car speed and gear ratio dampening the bucking effect. If I apply throttle the bucking stops. It is not due to driving at too low of speed for the gear (lugging). I've reviewed other posts about this but I don't see where anyone came up with final answer(s) to this problem.
I have conducted CIS pressure testing several times now. Here are my current values in PSIG:
*System Pressure: 70 (fuel to WUR shut off and throttle pressure regulator (TPR) return clamped) recommended range from manual is 65-75 psig
*Cold Control Pressure: 35 which is at the 35 psig upper limit at the ambient temp measured. Still using the original 001 WUR, still works so no reason to replace.
*Warm Control Pressure: IDLE 42 (recommended range 40.5 to 43.5 psig) this is measured with throttle in idle position (TPR affects warm pressures)
*Warm Control Pressure Part Load: 51 (recommended range 49-55 psig) this is measured with throttle partially open to achieve highest pressure
*Warm Control Pressure Full Load: 38 (recommended range is 37-43 psig) this is with throttle wide open.
*Leak down test I have 22psig at 20 minutes. I have verified the accuracy of my test gauge to be good.
As noted, this car has a throttle pressure regulator that works along with the WUR. As throttle position changes the warm control pressure changes.
I had a Pertronix ignition module installed when I first ran the car. Thought this could be the culprit so I have points installed currently with no change to the problem. Points, dwell, plug gaps are set to spec. New Beru wires installed, firing order checked several times. New Bosch injectors. I have checked timing several times also, spec is 5ATDC with vac hose connected and 35BTDC @ 6000 PRM with vac hose disconnected. My altitude is 4500 ft so I could have a little leeway to advance timing but for now I'm trying to stay at spec. I installed an AEM air fuel ratio (AFR) meter to allow adjustment of fuel mixture and real time monitoring. I currently have at idle an AFR of about 13.7 which equates to about 2% CO (spec is 1.0 to 2.5) Unknown if my AFR is accurate but when run rich I can tell it is by the exhaust odor being more pungent.
I have conducted a smoke test of the intake and find no leaks. No pop off valve installed. I have checked the air flow plate to be correctly centered in the venturi, at the correct height and free movement.
Has anyone resolved this bucking/jerking problem in early CIS cars?
If you have let me know, if you have other suggestions or thoughts also let me know. Thanks for your time. JK