EPC light coming up - P0221 throttle position sensor.

my rs has this typical problem which is intermittent. Normal driving there is no error. if you drive hard especially on second gear, suddenly epc light glows and goes into limp mode. on scanning i got the above error. Switch off , switch on , it works perfectly normal. This happens randomly.

What could be the problem ?

Edited 1 April, 201115 yr by v&v