After replacing the head gasket now will not start

2 weeks ago I replaced the head gasket. Along with that I replaced all the usual gaskets (valve cover, intake/exhaust, water pump, etc.) I also replaced the oil pressure sensor and crankshaft position sensor. Today I received a new valve cover so I could finally finish the project. Go to start the vehicle and it cranks, but refuses to start. First thought was fuel. Checked the fuses; good. Popped off the rail; definitely getting fuel. Next I rechecked the timing, twice. Third I ran through and checked every wire, ground, and connector. All good. I removed the coil packs and spark plugs one by one. All getting a spark. The weird part to me is with one spark plug removed and ground out to the manifold. The vehicle starts. Runs bad but starts. What is the issue?