Same exact issues can occur if you swap the #2 and #3 plug wires...i.e., it's 1-3-4-2 in the COUNTER-clockwise direction.
If you get #2 and #3 swapped (by putting them on in a clockwise direction, easy mistake), it will do exactly what yours is doing.
Start there. I hope for you it's that simple, because 2 minute fixes are awesome.
- Brian