[TheRiddle]

118001 Mixture too lean
118401 Mixture too lean, large deviation

sporadically the idle is over 1300rpms

your best shot?

Vacuum
injectors
fuel filter (or contaminated gas)

car runs fine
no shaking/strange behaviours at cold start
maf readings are within normal parameters

[mDrive1]

fuel tank breather valve?

[TheRiddle]

Originally Posted by mDrive1

fuel tank breather valve?

Bimmerlink didn't gave any specific issue, I haven't tried with Ista yet..
i remember that INPA used to give a specific error on my e46 for Evap and tank breather valve..

is there a direct way to test it via Bimmerlink on the go?

[mDrive1]

Ista has a test option, but you only hear a click sound, so I don't think it checks the integrity of the membrane at all. However, many other things could be leading to your problem. good luck troubleshooting. Let us know what you find.