2000 celica gts idle problem

[insane575]

So I have a 2000 celica gts with a cai and catback evo exhaust. My car idles perfectly all the time except when I fill up all the way. When I'm running low and I go to fill up and I fill up till the nozzle auto shuts off I go to turn on the car and it won't idle. I have to keep giving it gas. But I fill up a gallon less than full then it also happens but not as bad. It'll idle at 800 rpm. It idles bad for about the first 5 minutes after I drive away from the gas station and then idles fine. What is happening? Btw my o2 sensor is out. Could that be the problem?

[Bitter]

fix the O2 sensor, you probably have the butterfly valve connector plugged into the evap vsv.