I have a 2005 mustang gt 5speed that ive had some issues with performance wise! My idle when taking of in first gear woukd drop almost like if the the car wanted to die and ive cleaned the throttle body and maf which kinda helped a bit but the car someone ends up running very sluggish very bad throttle response ect and even affects the shifting.. Well about two weeks ago i thought maybe the drop in K and N filter might have something to do with it and i replaced it with a stock filter cleaned the throttle body and sprayed the crap out of the maf didnt bother resetting computer just to see if theres a difference and let me tell you ive never felt the car run so amazing! I was very happy and the response was there the shifting was crisp for some reason i mean it was a different car. After about two weeks its started to i guess fade?? Alnost like its slowly going back to how it was?? No check engine light nothing! Today the car felt sluggish almost how it delt before i just cant understand whats going on. It ran like a dream for about two weeks and now its back to how it was? Please help! Ive replaced the spark plugs a few months ago, fuel filter 93k miles any help would be greatly appreciated!!