914 spitting / cutting out only when warm, lean or rich or ignition Options

[Medtner3]

My 2.0 D-jet has problem : Idles smoothly at start up and cold. As it warms up, it "spits" and cuts out and gets progressively worse the warmer it gets. Is this a CHTS problem maybe? I will test the ohms today and repost.

I thought this would be an ignition system fault such as a bad rotor / distributor or plug wire, but I noticed it gets twice as bad when I put the air box on.

I can only increase the idle at the throttle body and not decrease and I believe the ECU knob is at the center (there's a mark on mine?) :

1) what would the default setting for ECU knob be and how to find it;
2) what is likely causing the "spitting"

I don't see any vacuum leaks at all , and all my injectors are brand new, timing seems right as rain, and dwell and points are spot on, and my air temperature sensor is showing 195ohms, my CHTS is new. The AAR valve is working.

Starts smoothly and idles low around 400 rpm not spitting at all , but after about 20-30 seconds idle jumps to 1100 rpm and starts "spitting" and so checked AARV it is closed

Thanks in advance