I have the exact same problem!!!!
Nissan Micra K12 1.2 Automatic.
Problem started straight after a service & MOT last week. Car went into limp mode - wouldnt go above 2000rpm. Took it back to the garage and they suggested a fault with the throttle body. Wasnt convinced, so took it to Nissan. They also said throttle body and quoted me £800.
I have an OBD reader, and I was getting error code P1122 - throttle position sensor (low voltage).
I bought the throttle body off ebay (new) and fitted it myself.
Car will now rev to about 3500rpm but throws up error code P1121 - throttle position sensor (high voltage)
If I reset the error, all is good until i turn ignition off and back on again.
Should I change the accelerator pedal? - I have had this out and looked at it. Checked it with a multimeter and the potentiometer seems to be working (but I dont know what values to expect).
Is there an air flow meter in this car? where is it? - could this be a problem?
Any thoughts on this would be appreciated.