HouseCallAuto 7/29/2012One of the spark plugs may have been cracked while installing, one of the spark plug gaps may have closed because you maybe dropped a spark plug as you were installing it. One of the ignition wires may not be seated all the way. Remove all the parts again, install 4 new spark plugs and see.
HouseCallAuto 10/4/2012Have you noticed any unexplained loss of any coolant from the radiator over time? This question goes to possible head gasket seepage of coolant into a cylinder after it is parked for the night.
Yoiu need to plug in a code reader and see if any fault codes are stored that might identify a potential misfire on a specific cylinder.