[Uhehner]

First guess - bad plug, coil or injector.  Sounds like one cylinder is dropping out. Also do a check of the error codes to see if it's an electronics problem. There was a recall years back for the camshaft position sensor but 2004 should be the new type. You will need a good tech to check the spark plug voltage on each cylinder and one with a laptop to read out ALL the computer information.  Capt. George