hi paul i had very similar problems with my corolla tsport, my car kept runing slugish etc and had it plugged in a t toyota, they said it was an O2 sensor had that replaced they said it was ok 20mins after pickin it up it happened again, that nite we called the AA and they pluged it in and it turned out to be the Air flow sensor not the O2 sensor which i paid big monies for!! hope this helps, feel free to ask any questions, Regards, Luca :)