Engine hunts when in drive

Hi i have a freelander 2012 HSE SD4 auto, that has had a issue for the last three months that when stationary in drive or reverse the engine starts to surge and hunt, but not all the time it does not do it when cold but starts after a few miles sometimes it may only do this once or twice when driving for quite some time, is there any sensors in the gearbox that may bee playing up, and causing this intermittent problem, any suggestions please .

First, when was the gearbox fluid replaced? It should be done much sooner than LR 150k miles interval, cutting that by ⅓ is a sensible precaution, so if its done more than 50k and the box fluid is original, get it replaced, and see if the issue goes away.