Why does a car stall after you fill the gas tank?

Because when you fill up the tank there is a evap system which takes the fumes from then tank and runs it through the engine and burns them if the valve is bad in the take it will let you overfill the tank which will saturate the canister and when you start the car the computer thinks it is still sucking in fumes when its not and is making the car run rich will or can cause it to run sluggish or stall when not on the throttle the only way to fix this is to buy a new gas tank or you can just not fill the tank all the way (i have the same problem and i just dont fill mine all the way its cheaper)