2003 Dodge Caravan replaced engine

This may be more than you wont to take a stab at but I changed the engine in my 03 grand caravan the old one started knocking. The replacement will not start. I changed the: coil pack, plugs and wires from the old engine because I know they are still good. I tried pulling a plug then putting it in the plug wire it did not fire. I pulled the fuel line loose and it had pressure on it. Do I need to do something to reset the computor? Can the fuel rail or fuel injector go bad setting in the junk yard? Any suggestions would be apreciated.