After i gave mine to a garage, god knows what they did it was never the same acceleration! My guess would be to do with oil in places where its not suppost to. try to get a car behind you (at night time) then do a kick down and see if there is smoke or shit out the exhaust. i know mine did this for a while untill i cleared feed/return lines and then it was abit better. Maybe you could try this. Also check if there is oil in intercooler piping.