Shogun The valve that is missing is a hose is the fuel pressure valve. What happens when the hose is missing on this valve. Does it make the vehicle hard to start? Also wouldn't it cause the engine to run and idle poorly?
If the FPR is disconnected you will have two problems:
1) The FPR will always be closed thereby providing maximum pressure to the injectors at all times. It should open under vacuum...such as at idle.
2) You will have a vacuum leak because the vacuum hose is unhooked from the FPR. This could explain the poor engine performance.