Is it an actual felt misfire (ignoring the SES light)? If not, the misfire detection system may be malfunctioning and the misfire code not real.
When you change or disturb a crank position sensor, you have to do a crank position sensor relearn of the output waveform. Comparing to the stored waveform is the way the PCM knows when there is a misfire. If everything isn't perfect for whatever reason, the PCM reports a misfire (even if it is something else).
PCM can even pick up on the change in waveform from excessive main/rod bearing clearance so it is very sensitive. That was a problem I had with my Blazer when I first bought it (only 65K miles). Other things like belt driven accessories, and flex plate can also cause misfire codes by jacking with the engine balance. This is no secret and is in the factory manuals.
Not sure why everyone always goes for the crank sensor replacement first. It is a really trouble-free simple devices with no electronics in it.