Thanks for replies.
AA chappie was unable to do a diagnostic check as his computer thingy would not read anything. Would Lexus use the same equipment?
Because the accelorator would not do anything unless you put it all the way to the floor (is this what happens in limp mode?), he suggested it could be the accelerator sensor as well.
Now that you have had a new one fitted, what difference have you noticed? Mine seemed ok driving to work this morning, which was after disconnecting the battery.