My vehicle only has apx 68000 miles on it. I have a current issue were whenever I am driving at a constant speed and I wish to accelerate the car to kick in over drive or to push the pedal, I get a delay of a second before the car reacts, but at the same time, I hear a semi loud popping sound from the engine area, it only does it whenever i am in motion.it sounds like a escape from the muffler but i doubt that. It may be a misfire of a cylinder or I may need a tune up to change cables and spark plugs. amd while my car accelerates and gains speed, i feel as if the engine isnt pushing as smooth and fast as it should be. may it be the misfire causing this poor performance? need some advice before going to a mechanic please.