In the past several months, when I start my car cold (after it sits for a day), it will start fine and high idle fine, but as soon as I drive it, it will backfire, sputter, won't accelerate in any gear above 1200 rpm. After it has ran for about 2 mins, everything clears away and it runs perfect. My mods are in my signature below. Any help is greatly appreciated, thanks! Guess I should mention that the car has 50000km's on it now, with the original plugs.