it sounds like low fuel delivery.
did you replace the vaporizer with an oem one?
pull the supply hose from the mixer and turn on the system and see how much comes out, you should hear it rush out fairly well. it also could be a bad mixer diaphragm. i'd pull the top of the mixer and make sure it's not torn and the bullet shutoff button is clean and still intact. make sure the vacumm lines are in good shape.