Xj350 V6 petrol 2004 engine stuck on idle

Hi , i have a v6 3.0 petrol with 137 k miles. Fault code for APP P1344 . I have checked the wiring , cleaned the sensor tracks and no fault found. Engine stuck on high idle and will not rev st all. Checked all voltages with meter not scope yet but all look ok. Switch off remove key , restart with key ok again for a while
. DSC and hand brake warnings and engine system.

Do these go into fault mode caused by a faulty APP sensor ? Do these APP sensors fail at this milage ?

Can not find any other fault codes and does not always go into fault mode. When fault clears on restart drives perfect but need to cure this as could be dangerous when happens on the road.

Any help please with many thanks in advance