I would always get a proper diagnosis and fix the problem, rather than throwing parts at it in the faint hope that I hit the jackpot and found the failed part. If it all of a sudden started running poorly it doesn't sound much like plugs. More likely a vacuum leak.

At least in Vegas you can go see a show.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue