Has it only started doing this, or have you been adjusting the settings?
How does the boost valve work. I am only familiar with T5 T7 valves, which you don't have.
If you have lifted base boost past the recommendation, it can mess with the boost system.
If it is a violent "fuel cut" it probably means that the engine is "detonating". Hence cutting the boost to "save the engine". If the MBC is too open it can cause this.
But we are working in the dark without more info, history.
I have really only done ECU tuning on 9000 Trionic ECUs.
03 V6 Renault Laguna! (best worst car I have owned!) 06 Merc E350, 11300km, 93 9000 griffin 2.3 St-II. 93 9000CSI na man,370,000km. 92 900 S LPT vert.