Downhill and zero throttle tuning help needed

I am road tuning an NA MX5 with a Link g4x pnp ecu. Most things have worked well as per following the instructions from the course. Can someone guide me to where in the courses I can find how to tune for when coming off throttle or going downhill with zero throttle. Currently the car is very rough in these situations, shuddering and shaking as I am going downhill. The Auto Tune on the ECU can't seem to deal with it and the Lambda shows as 1.5, lean. Which is probably what it needs to be. It also behaves like this when I come off the throttle quickly but still in gear during normal driving.

Any guidance would be appreciated.

Is overrun shutddown enabled?

Thanks for getting back to me. I am not sure I will check that out.

If you are not disabling fuel on decel, you'll need to tune he areas of the fuel map encountered during decel just as you would areas you drive through. With the vehicle in gear, decelerating, you'll generally achieve low intake manifold pressure than during any other condition. I do not suggest attempting to auto tune in that area, and you may also need to tweak your MAP axis break points so you can more accurately tune for that specific condition.

Thanks for that information. I have now read about that part of the map and I did have Overrun Fuel Cut - ON. The issue is more when I am driving and descending down hill, the TPS is at 0% but the RPM is higher at say 3000RMP, as the car is just engine braking downhill. And during this time it is jumping and shaking as if someone is applying the breaks intermittently. Any direction you could point me in for how to set up the ECU for this situation? Thanks!

It sounds like you may be on the precipice of your decel fuel cut threshold and may need to alter it so the engine consistently goes into and stays in decel fuel cut, or does not cut and you'll need to tune the fuel table in that area.