[mx5_seoul]

hey guys im having problem with my car. i did a engine swap recently and finally got the car running but while im driving the car i cant put the gas pedal all the way down because if i do the car bogs out, but if the gas pedal is down only a inch then the car moves but if i press it anymore it bogs out again. can it be the o2 sensor and need to be replaced?
thanks for the help in advance :]