Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe
Flight Crew Diverted; Flight Crew Landed As Precaution; Flight Crew Landed in Emergency Condition; General Declared Emergency
Aircraft
On approach; flaps 45; the autopilot kicked off so we executed a missed approach.  On the missed we noticed some control pressure irregularity but got the aircraft under control and decided to try it again without the autopilot.  On the second approach at flaps 45 we got a STAB TRIM runaway.  The First Officer (FO) ran the Immediate Action items and QRH for STAB TRIM runaway.  The aircraft was difficult to control in a flaps up configuration.  Weather was starting to move toward the field. At this point we decided to divert and declared an emergency. While enroute we communicated to the Flight Attendant (FA) the situation and time remaining. Landed flaps 20 degrees per QRH with no further issues.
[Report narrative contained no additional information].
CRJ-200 flight crew reported they got a stab trim runaway and chose to divert to a more suitable airport.