Valve stem seals, misfire question

[bignasty27]

2009 BMW 4.8 135kms

Have always had a slight vibration at idle and "PUTT PUTT" out of the exhaust. Check engine light comes on and its MISFIRE cylinder 4. Great, finally get CEL and its going to fix my issue. Replace all ignition coils and plugs but "PUTT PUTT" remains. 24 hours later, MISFIRE cylinder 4. Take it back to the BMW INDY, runs it through a bunch of tests and numbers check out as normal, no vacuum leaks. Indy thinks it is related to the Valve stem seals. I do not get a bunch of smoke at idle or any other time. Yes, consumption was high but changed CVV and reduced consumption to the point where I am adding only 3 quarts per 5000km. I change my oil every 8000kms.
My questions is, can failing valve seals cause Misfires or is my Indy not trying hard enough to find the problem?
Based on the information on this forum, possible causes for my issue could be, fuel injector ( he claims he has never seen a bad fuel injector on this engine ), fuel filter ( claims there is not one on this model ) intake boot ( he did not do a smoke test ) and a couple of others that I have read.

I plan on taking it somewhere else for a second opinion.

Thanks!