OK if there's no top gear I'd 1st plug the car into a ford scan tool to see if the gearbox is in limp home or has another fault as top will be locked out in limp home. its possibly low fluid level but sounds like this would have been checked
Pedal position sensor - The pedal position sensor is located on the gas pedal. There are usually three wires used to determine the pedal position, a 5 volt reference supplied by the PCM/ECM, ground, and sensor signal. A factory wiring diagram will be necessary to determine which wire is used. Make sure the connection is secure and there are no loose wires in the harness.
Check for good ground using a digital volt ohm meter (DVOM) set to the ohms scale by connecting one lead to the ground at the sensor connector and the other to chassis ground - resistance should be very low. Check for 5 volts reference voltage from the PCM by using the DVOM set to volts scale with the positive lead at the wiring harness connector and the negative lead on a known good ground with the key in the run or on position .Check for reference voltage using the DVOM set to volts scale with the red lead on the reference signal and the negative lead on a good known ground with the key in the run / on position - the signal voltage should increase as the throttle pedal is pushed down further.
Typically the voltage ranges between 0.5 volts with the pedal not pressed and 4.5 volts at wide open throttle position. It may be necessary to check the signal voltage at the PCM as well to determine if there is a voltage difference between the sensor and what the PCM is reading. The position sensor signal should also be checked with a graphing multimeter or oscilloscope to determine if the voltage increases smoothly with no dropouts throughout the entire range of motion. If an advanced scan tool is available, the positions sensor is usually displayed as a percentage of desired throttle input, make sure the desired value is similar to the actual pedal position.
there's also a bunch of recalls so ensure that these have been carried out
1996 (April '96-July '96): check for overheating of brake system.
1996 (2-litre with air-conditioning -Jan '95-Feb '96): air conditioning compressor may seize up.
1997 (built Jan '96-Apr '97): check optional child seats.
13-1-2000: 80,000 Galaxys, Alhambras and Sharans VIN TV000001 to YV509825 recalled to check for contamination of brake fluid through master cylinder vent. Brake master cylinders of older cars to be replaced.
23-5-2001: Build dates 1-1-1994 to 5-11-1999 2.0 litre and 2.3 litre petrol models with a/c: when engine rocks the fuel feed and return line may hit the a/c low pressure suction pipe, eventually leading to abraded fuel lines. Fuel lines to be inspected and replaced as necessary and spacer clips to be fitted to all.
6-10-2003: 7,866 Galaxys VINS.....2R to .....3T recalled because wiring for curtain airbags may be transposed. Check and if necessary fit wiring adaptor. TSB at some time between 2005/2006 to replace faulty dual mass flywheels on post 2001 TDIs. 25/04/2006R/2006/034 FORDGALAXYflywheel may fail build dates 01/11/200231/08/2003