seat leon epc problem!?

i own a 2001 seat leon 1.6 16v (aus) the problem is occasionally when i'm stopped at a juntion the throttle stops working and the epc light comes on. i have to turn engine off and on a number of times to get it working again. i havr been told a new throttle position sensor will cure it but at the cost of over £300 want to be sure this is true. Or if there is something else i can do?

paul
December 2007