Check engine light on, please help (V8 5.0i)

[J.Seven]

I am in a distant part of Africa, 3 days by car from the nearest BMW car Dealer.

I have BMW X6 from 2010 with 50i engine and 29.000km on the clock. The check engine light is coming on , each time I press the throtle, mainely on 3 and 4 or 5gear from 1500rpm, engine loosed power and seems the engine is working on 7 or 6 cilinders! I turn off and then on th engine , lights goes off and engine is normal again. If I cruise in 1 or 2gear from 1000rpm to 2000/3000rpm and then engage 3 gear, the check engine not always comes on, so I try to drive in manual most of time and passing gears only at 3000rpm +, so the check engine does not come on. But at lows revs and high gear check engine light comes on immediatly, no matter in "D", "Sport mode" or "manual".

Can I have problems with injectors? Fuel pump? High pressure fuel pump? I believe it´s not the MAF sensors as both were replaced a year ago.

At high revs, 4000/5000rpm, engine is pulling strong without fails, but after a while, even at those revs, sometime the check engine light comes on again.

What can be the problem before I decide to make a long and very hard trip on very bad roads to get to BMW dealer. Thanks in advance.