ok i've had the gearbox replaced and torque convertor and the throttle body, and then the maf tube had fallen off so that was re-attached. Its basically ok now and this is an intermittent fault that only seems to happen when full load in car and going up an incline/hill it still moves forward but seems to slip on the gear it revs high and then suddenly seems to kick in with a bit of a thud. Any ideas would be appreciated? Also is it possible to change a gearbox without changing the fluid as i had wondered if that was the problem?