ML350Cdi BE now replaced, E220 2013MY just for a bit.....
It has been known for fitting odd tyres on the X3 to cause strange power problems, down to traction control seeing different wheel rates and cutting back the throttle assuming there is traction slippage.
'21 C300 Coupe, '20 SLC Final Edition, Peugeot 208 (hers!) and a new Ford Kuga in Russia
Oddly, I had exactly that problem with my Qashqai in Russia as I was running the last couple of weeks of the trip in summer with studded tyres (too much hassle to change them for just two weeks as I'll be using them properly in january) and the traction control detected a loss of traction due to the studs and cut back the power at various times when accelerating! Lesson learnt! never drive on studded tyres in summer!