it's worth the $$ to visit the dealer - but, just for diagnosis. They'll probably charge you $85-$100 for the diagnostics, but they have the best chance of nailing the problem. Then what you do is order the parts yourself. Infact, work a deal with your service advisor - you get the parts cheaper by yourself and they install. They may say you get no warranty - but, hey if the parts are OEM, they have the OEM 1yr warranty on them, and the shop has to warranty their work anyway. Bottom line, you win in both cases and your SA wins also, somewhat.