rangerover 4.0 se in limp mode

help please, i have a rangerover 4.0 se, which seams to have gone into limpmode, it ran great until it came up with gearbox fault,only once though, i had it on a diagnostic machine,but it didnt show a fault,but now it wont rev over 3000 it starts to misfire?but it starts ok, can anybody give me an idea

maf senser is first go at it. is it on gas? and post in range rover sec