Try to remove vanos (it's easy) clean it and swap places. Best before you remove them to check on diagnostic which giving you trouble. Than clean and swap. And see if problem comes back. I'm not 100% sure but if intake vanos then misfairing and cutting engine straight after you just start driving. If just after short trip start misfairing then exhaust vanos. That was on my 325 n52 engine.
I know this should be in technical post.
