Done a bit of fiddling.
Went into the diagnostic menu and found that the TPS had a reading of 13 at closed throttle. I've adjusted it and it now reads 17 at closed throttle, 98 at open throttle, but hasn't made a difference

Noticed that when I go into CO1 and start the engine to see the rev counter, it just reads 0, no matter what I do with the revs. Could this have anything to do with my problem?