Been having this issue since i tried out map 5. I use the mix recommended of e85 and e93 premium and have the upgraded and gapped spark plugs but pretty often when i accelerate quickly i get a very bad jerking and bucking fro mthe car that happens 3-10 times and then stops and accelerates normally. I have tried different fuel combos and octane boosters and have had no success. Anyone had this issue or know a fix?