Hey gues not very good with cars but I need help please. I have a 2014 fiesta st that just started stuttering when I aggressively accelerate. I took it to a shop and they told me it's due to not having enough back pressure.(I know it's stupid to not have one) I don't have an exhaust on it currently because I just sold mine.i don't drive it very often but I've driven it maybe 8 times without the exhast and it worked great still a bit load but great then all of a sudden shuddering unless I drive like an old man. Any thoughts or ideas and I would love to hear them I don't want to have to buy another exhaust just to sell the car soon if someone has any other ideas what could be wrong I'd live to hear it.