range rover 3.9 se engine probs...help

I have a '93 3.9 vogue se rangie with a 5am air flow meter. The engine will run fine until I get to about 2 thousand revs and then it will run out of steam and feel under powered, even under kick-down when overtaking. Also, the engine revs will hunt at tickover, even as low as two hundred revs and then go back up again and then come down and sometimes even stall. In traffic this can be very annoying. when going back into neutral when at tickover the revs will go above one thousand revs and then come down again to about five hundred, but then sometimes will stall again.Someone has told me that this is the air flow meter, but it could be something else?any suggestions would be most gratefully received by new range rover owner.best wishes, scott