Unfortunately, the Dealer is correct, this can be any number of things. More commonly though, given the year of the vehicle will be a "misfire" of some kind. Very commonly, this is a failed Ignition Coil
. This means the coil is not sending power to the spark plug
and results in the cylinder sending unburnt fuel through the system. This can result in Catalytic Converter
damaged, which will produce a foul smell. This can also be the case of worn spark plugs. If the engine
were under load (like speeding up a hill) and the spark plugs are not firing at full capacity, again, some amount of unburnt fuel is sent through the system. This can also be a problem with the Mass Air Flow sensor. With this sensor faulty, the fuel and air mixture will not be correct and can affect engine performance. Unfortunately, again, no way to know for sure. At this point, the best bet is to have the Diagnostic Trouble Codes (aka "P-Codes") scanned from the on-board computer so we can see what the computer is seeing. These p-codes will point us in the direction of the part or sensor that has the problem and from there, we can more accurately and efficiently diagnose and repair the problem. You can have these p-codes read FREE (except in California) at any local "big chain" part store (ie. AutoZone, PepBoys, Advanced, etc). If my answer has helped you, please help me and rate or accept my answer.Rating or accepting my answer does not cost you extra. It allows me to be credited for this Q&A. If you cannot rate or do not see where to rate, please let me know! You can ask follow-up questions after you rate or accept. Thank-you!