Car has started running lousy and i changed the basics after the scan like plugs wires coil pack finally checked injector #3 and found it had no negative injector pulse checked the wire all the way to the ecm and it lit up the whole way is this telling me i need a new ecm or has anyone experienced this it shuts down the cruise control and my gas mileage has fell to 15 from 28 ive ordered a new ecm hoping that will be the fix