scaned my car the other day as its under preforming fine when its cold but soon as it get past 70 ish on temp gauge it goes really flat and hesertent these are the codes i got .should add its a mk3 2.0 8v been converted to vr6 655535 ecu defective 00515 hall sensor -g40 open circuit/short with power 00553 mass air flow sensor -g70 short with ground error occurs intermittent 00513 engine speed sensor g28 no signal any help would be great