2002 tundra 4.7L Throttle body

Hello. So I've done everything possible to try and fix the low and rough idle during initial start up. Cleaned the throttle body,cleaned and regapped the plugs,coils are new, MAF sensor cleaned. If I warm up the truck and reset the idle by turning the key off and on twice and letting the computer re-learn the idle it runs perfectly. My mechanic says it's probably the throttle position sensor. Can that be replaced or will I need to replace the whole throttle body assembly? Please help. Thanks.