the car starts to hesatate when it hits around 3k it only use to do it in the morning when the car was cold and the check engine light was on but when u turn it off and on when it warms up the check engine light goes away and it is fine but when i put the new sensor on the check engine light doesnt come on anymore but it still hesatates on the gas sometimes around 3k when i push the gas and let off and then push again what could it be???