quick connector leaks gas at fuel rail

My 95 LSS has those plastic quick connect fittings on the gas rail at the injectors, they have the plasic clip that you squeeze to remove. The plastic fitting connects to the fuel rail on the rear side injector feed leaks slightly when the pressure drops while the car is off. The fittings are not very sturdy and they have some play up/down and rotational. The fitting looks to be heat shrunk on plastic tubing that comes off the main gas line. They do not look easily replaceable without going to the dealer. The fitting does not leak while the ignition is on or car is running as the system is pressured up. Does anyone have a suggestion on how to replace this fitting without going to a dealer and spending 2 or 300 bucks?

Thanks.