I have a 1979 SB Vert and am having problems with it stalling after it warms up a bit. I have replaced the injectors, fuel pump and relay. It runs fine for about 20 minutes and then when I take it around the block it just dies as though it is not getting fuel. After it dies, it will crank back up but after about 1 minute it dies again. Any thoughts, recommendations or suggestions would be appreciated.