me-david

I am experiencing a fault that only presents itself when starting gently on a slope (forwards or reverse). When the oil temperature is cold it will happen on slight slopes, but requires a steep slope when the oil temperature is up to 100degrees C. The car stays in gear, but all drive/momentum is lost with a significant jerk and the brake pedal depresses itself . If I maintain throttle the drive will pick up again and move off. If I start with gusto the problem is not there. Typically it will occur at 1000 to 1200 rpm and might be preceded by a slight roughness in the drive. Essentially the slope has to be steep enough to be able to start to creep at revs of 1000rpm. When the engine is warm this means a steeper slope. I have had the transmission fluid and filter changed with no effect. A transmission maintenance company believes it is linked to the ABS system malfunctioning on a hill start and not performing correctly at low speed/revs. The problem would be significant if trying to extricate from kerb parking on a hill with vehicles fore and aft. Equally it has been a problem when trying to ease across traffic from a sloping side road, where one loses momentum at the least convenient time. Then again starting off on ice or snow would be likely to cause a problem.
Has anyone any thoughts on this problem?