It may be the computer that controls the fuel injection.
My 2002 Dodge RAMwagon started having problems with the engine suddenly quitting while driving down the highway or street, and then it would sometimes start up again as if nothing had ever happened. Turned out to be the failure of the master computer. Chrysler-Dodge had no replacements available for a month. The tsunami in Japan had wiped out the manufacturer of the component. afte renting a car for nearly a month, the dealer finally admitted they didn’t know when of if a replacement would be available.
I finally bought a remanufactured part from a company in Florida and had the dealer install it. A year later and the dealers tell me they now have the part in stock again.
Because the master computer wasw responsible for the O2 sensor and many other sensors, its intermittant failures misled the dealer mechanics for awhile.