I have recently installed a techedge wbo2 sensor to begin tuning the car. As it is however the tune was running stock and everything was working properly. However on the trip home it would lean out heavily on part throttle until the motor would start shuddering. On idle the afr was sweet and if I mashed the pedal it would run fine aswell but anytime the pedal was only on gently it would progressively lean out. Any ideas on what this could be? I have already tried unplugging the battery and letting the ecu reset but had no success

connect the NBsim wire to the wiring for the stock HEGO sensor.

I had/have a similar problem. Leans out like that. My NBsim is all hooked up so dont know what the problem is and no-ones figured it out yet. We checked all fuel and spark but no issues there so beats me why it does it. Only happens on petrol so I can get around on gas no worries.

checked injectors?

Is the car modified, or stock? If modified, what have you changed? Is it when you are gradually accelerating from a standstill and when increasing speed slowly when cruising? Can you accelerate at speed, then cruise with no problems, or when you are cruising without any further acceleration, does it still do it? Did you replace your HEGO sensor with the wideband sensor, or did you weld a new bung in into the headers and are still running the stock hego?

If you can cruise and it maintains stoich, but gently apply throttle and it leans out, it sounds like a tip-in issue, aka accel enrichment. The same as slowly accelerating from a standstill. But this should only be if you've made changes to your engine, such as injectors, throttlebody, etc.