2008 Kia Sorento LX

Hi everyone, I drive 2012 Kia Rio, i noticed the oil light turn on when I stopped and if I want to move again it off but must time when I want to move , I won’t be able to accelerate until I switch off the AC , I was told its the vvti sensor , I change it and I changed the oil with filter but there is no changes . I really need someone to advice me ,thanks .