Weird idea, crank position sensor, VSS?

Or if you would like to join in the continuing hunt for misfire codes how about a your crankshaft pulley (harmonic balancer). I have to say though, I would be looking at the coil pack (just 'cause 1 and 4 fire off the same coil. Did you replace the mounting plate when you replaced the coil pack? Maybe a crappy ground (had it happen on a Saturn a couple of years ago).