Sounds to me like you are having a vaporlock problem of sorts.. i would check to see if the venting in the fuel system is ok.. next time it does that, try loosening the fuel cap and see if there is a large rush of air into the fuel tank.. sometimes ive even seen it so severe that you cant get the cap off until it vents for a while.. if that be the case you may want to get a vented fuel cap, or find out how the fuel tank is vented and find the blockage.
