My fuel efficiency (mpg) is very poor my vehicle, i have 9.4 mpg power loss and the mpg's shown in the official manufacturing web page is epa est. mpg 22 city/30 hwy. https://www.jeep.com/jeep-capabilities/fuel-efficiency.html additionally i am experiencing loss of power during the start of the drive or when starting again the vehicle's progress after stopping at a traffic light or at the time of revamping a vehicle, i have also experienced shaking as if the engine of the vehicle were going to turn off, without going through and the "check engine" indicator does not activate.