hi lad, ... just some info..if the mechanic has the specific diagnostic for your gp800 he can do
Zeroing the throttle/Resetting the throttle valve position signal (TPS reset)
it states how to in the gp800 workshop manual, if you want a copy PM me your email addy.. the below taken from the manual for you to check or print off so the mechanic has the correct values to check scoot
on the throttle body of the gp800 you have
INTAKE AIR TEMPERATURE SENSOR
-10° = 9600 Ohm
0° = 5900 Ohm
+10° = 3800 Ohm
+20° = 2500 Ohm
-30° = 1700 Ohm
THROTTLE POSITION SENSOR
With the switch set to "ON" at a variable voltage
between 0.7V and > 4V between pins 23 - 3 on
engine-side wiring.
Ground insulation of pins 29 - 32 - 3 on engine-side wiring
STEPPER MOTOR
Resistance engine-side connector between pins
19 - 9 ~ 51 Ohm
Resistance engine-side connector between pins
18 - 17 ~ 51 Ohm
as well as the FUEL INJECTOR Resistance at terminals: 13.7 ÷ 15.2 Ohm
also the two coils
H.V. COIL
Primary winding resistance: 520 ÷ 620 mOhm
Secondary resistance: 6830 ÷ 7830 Ohm
Spark plug cap resistance
~ 5000 Ohm
you could also disconnect the ENGINE REVOLUTION RPM SENSOR CONNECTOR and clean that up AS THIS IS A CAUSE also
remember that EMS failure is more likely to be due to the connections than to the components
YOUR MANUAL STATES IN THE TROUBLESHOOTING SECTION:
Engine stops at idle OR ENGINE DOES NOT HOLD IDLING/ IDLING IS UNSTABLE/ IDLING TOO LOW (possible cause first highlighted then CHECK OPERATION OF)
Presence of faults detected by the self diagnosis
Pump relay ..HV coil..Injector..revolution timing sensor..Air temperature..Coolant temperature..
Ignition efficiency Spark plug ORIgnition timing
Correctness of the parameters Throttle valve position sensor..Stepper..Coolant temperature sensor..Intake air temperature sensor
Intake system cleaningair temperature sensor..Intake system cleaning Air filter..Diffuser and throttle valve..Additional air pipe and Stepper
Intake system sealing (infiltrations) Intake manifold - head..Throttle body - manifold..Intake sleeve.Filter box
Fuel feed (low pressure) Fuel pump..Pressure regulator..Fuel filter..Injector capacity.
THATS IT

so a clean up of throttle body sensors probably first, and a multimeter test on components would be best bet..
