XSeries-forum

Put it in manual mode and slow up in 2nd.
Then manually put in first.

If it lurches, it will do it then..

You can also cycle between 1st & 2nd whne stationary and feel for the jolt between gears.
Should be nearly seemless and fairly un-noticeable...

Also check lock up clutch works OK.
Get to 55mph, let off throttle slightly and watch revs die back, then gently accellerate.
revs should stay consistent as you accelerate up again. (MPG meter will drop)
If there is any slippage then this could point to LUC lining issues

I agree with the 55 mph bit. Mine seemed like a misfire at that speed and it also juddered when going from 4th to 5th. Didnt do it on the test drive which was from cold to hot circa 45 min. It scanned clear as well.. It only started doing it a week after I bought it.
Dont forget the usual checks- wheel wobble when braking, every switch/dial/knob, climate control, parking sensors, music system ( my tape deck doesnt work for some reason and I have loads of tapes-retro).
Another obvious thing - are the tyres/discs good? Cash can soon rack up when doing stuff like that..