2002 Ford Focus Car won't run after rebuild

So my focus will start but won't stay running. Sometimes it won't start at all. Sometimes if I give it a little gas I can keep it running but once I take my foot off the gas it dies. When I first pulled my car in my garage it was running but now after changing the head gasket and all the other gaskets, the battery, sparkplugs, fuel filter, radiator, radiator fan, all the hoses, timing belt, serpentine belt, water pump, and fuel injectors it doesn't want to run. I'm not getting any codes, the fuel pump still seems to work after hooking up a gauge to it (40psi), I'm getting sparks from the coil and wires.I'm not sure what my problem is?