Ok here is what I have found. The fuel filter had just been replaced and the fuel pump assembly had been replaced over 1-1/2 years ago. The engine was over a gallon low on coolant. After I put coolant back in it, it didn't shut off anymore but still has the hard start issue. I connected a fuel pressure gauge to the fuel rail test port and found that while cycling the key to the start position, by the time the fuel pump cycled back off, the pressure would only build to 12 psi. While trying to start it, I found that the pressure would slowly build and once it reached 15 psi, the engine would start but the pressure wouldn't exceed 25 psi. I decided to check the pressure coming off of the fuel filter and found that while cycling the key to build pressure, it didn't exceed 27 psi. The owner said that it has had the hard start issue for a couple of years. She said the problem she was having was with it shutting off every two blocks. That problem went away after I topped off the cooling system. I don't know how that would make a difference since I don't believe there is an overheat shut-off feature to the engine and this was happening even on cold starts. I believe it has a return-less fuel system since I couldn't find a return line from the fuel rail to the tank.
Upon further investigating, I found that it is return-less and it sounds like the regulator is stuck open. I'm going to drop the tank and try to clean the valve to see if I an clear whatever is sticking it open. If not then I'll be replacing the entire fuel pump assembly.
Matt