Just got back from towing a car trailer in my mates AU3 auto wagon around 1000kms. Not sure if the car trailer affects why there was an issue but thought would be good to add in case it may have an affect.

To begin with the car was faultless but slowly it started having intermittent faults at any speed under 70kph. It would cut the fuel so with foot on accelerator it would seem as if the car was in neutral with zero throttle.
It would then seem to get a burst of gas an resume speed but then once again cut out.

It did this until speed got back over 60 or 70 which took a while with only acceleration coming from the bursts of gas it was getting but once speed was back up over 70kph the problem was gone.

Why would this issue only be related to a certain speed and not engine rpm and does anyone have any ideas what could possibly be the issue here?