2004 Jaguar Xtype put a new throttle body and accelerator pedal and still will not go it's won't go

 

Toby, for what you are describing, I would be looking at the wiring coming off of the throttle positioner and following it back towards the firewall. Critters love climbing into the warm engine bay and since the insulation on the wiring is made from a vegetable base, they find it tasty. That has lead to lots of interesting issues like you are seeing. I would also check the fuse for the throttle control. Could be a very simple fix.