The box will not change from 4 to 1, it chages as the speed slows, it sounds as though you have the age old favourite, air leak causing a very weak mixture, but could be a few other things, like the maf needing cleaning.
At the rear of the cylinder head area corner nearest the coilpack, there is a pipe that runs from the pcv valve at the front of the engine towards the inlet manifold, along this pipe there is a "T" piece, these are always splitting, and cause what you have, as do sticking pcv valves(a valve that shuts off under a certain prerssure) in the front of the engine block, neither are expensive, I would look at these two first, and clean the maf with carb cleaner, then reset the KAM, by pulling the 2 amp violet fuse in the fusebox near battery, just pull out for 1 minute then put back in, this is the Keep Alive Memory(KAM), that stores the slight tweaks the cars ecu does for best running, it puts it into relearning mode.
tabetha