Sounds like the fuel vapor hose from the tank to the vapor canister is cut. If the line is rubber, I would think you could buy a piece of gas-line hose and get a couple of nylon coupler barbs to splice the two ends together. At times, the vapor canister is under vacuum from the engine and if open to the atmosphere, the engine will not run well.
If the line that is broken is nylon, it is only supposed to be replaced with the same type of line and fittings. These are usually only available from the dealer, but I believe they are not terribly expensive.