My 2004 jeep wrangler x is sputtering/skipping in park while idiling and while drving up the road holding a steady speed or slowly accelerating. it does not seem to sputter while coasting or accelerating hard.the check engine light is not on. i had it checked for codes and there are not any showing up. i changed the spark plugs ans spark plug rail, coils, ect. and put gas treatment in the gas tank when i filled up. i also cleaned the injectors with sea foam. i changed the oil too. nothing is seeming to work... does anyone know what the problem is? please help. thanks in advance.