A CRJ-700 INITIALLY HAD AN UNCOMMANDED PITCH MOVEMENT FOLLOWED LATER BY AN OUT OF TRIM CONDITION LEADING TO UNCTLED L AND R BANKING. AN EMER WAS DECLARED AND FLT DIVERTED TO A NEARBY ARPT.

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AFTER LEVELING OFF AT FL370; NOTICED THAT THE AUTOPLT MADE A PITCHING MOMENT UP OFF ALT THEN RECOVERED. CONTINUED CRUISE FLT. FURTHER INTO THE FLT; NOTICED THAT THE ACFT WAS MISTRIMMED; IE; THE BRICK WAS NOT CENTERED. IT TOOK 1.5 UNITS TO THE R TO BRING THE ACFT BACK TO COORDINATED FLT. FLT CREW FELT THIS WAS NOT NORMAL AND CONTACTED MAINT CTL. WE WERE INSTRUCTED TO DISENGAGE THE AUTOPLT AND RETRIM THE ACFT; BUT THAT LED TO UNCOORDINATED FLT SO WE RETURNED THE CTLS TO THE PREVIOUS POSITION. WE DECIDED IT WOULD BE THE CAUTIOUS THING TO DO TO SET DOWN IN ZZZ1 AND HAVE THE ACFT CHKED OUT. A SHORT TIME LATER; WE RECEIVED AN AUTOPLT MISTRIM CAUTION; SO ACCORDING TO THE CHKLIST; WE WERE TO DISCONNECT THE AUTOPLT AND RETRIM. UPON DOING THIS; THE ACFT ENTERED UNCTLED FLT; BANKING TO THE L AND R BEYOND NORMAL LIMITS. AT THIS POINT; WE DECIDED TO LAND IN ZZZ BECAUSE IT WAS THE CLOSEST ARPT WITH SUITABLE FACILITIES. LANDED WITHOUT FURTHER INCIDENT; NO APPARENT ACFT DAMAGE; NO PAX INJURIES. FOLLOWED COMPANY PROCS TO THE BEST OF OUR ABILITIES DURING THIS EMER SITUATION.SUPPLEMENTAL INFO FROM ACN 684044: SOON AFTER THAT; THE CAPT DISENGAGED THE AUTOPLT. THE ACFT IMMEDIATELY SNAP ROLLED TO THE L ABOUT 40 TO 50 DEGS AND DOVE. WHILE HE FOUGHT TO CTL THE ACFT; WE WENT THROUGH A SERIES OF VIOLENT OSCILLATIONS TO THE R AND L DURING THE NEXT 10-15 SECONDS. WHEN HE REGAINED CTL OF THE ACFT; WE KNEW WE HAD TO LAND AT THE NEAREST SUITABLE RWY. I TOLD CTR WE WERE HAVING A FLT CTL PROBLEM AND NEEDED TO LAND AT THE NEAREST ARPT WITH 7000 FT OF RWY. I ALSO ASKED FOR A VECTOR TO THAT ARPT. CTR VECTORED US TO ZZZ; WHICH WAS ABOUT 40 MILES TO THE W OF OUR POSITION. THE CAPT MADE SEVERAL DSNDING CIRCLES TO THE L TO LOSE ALT. I REPROGRAMMED THE FMS; GOT OUT THE APCH PLATES FOR ZZZ AND COORDINATED WITH CTR AND APCH. WE SHOT THE ILS AND LANDED WITHOUT INCIDENT. THE NEXT DAY WE WERE TOLD BY THE MAINT CREW THAT THE FLT CTL PROBLEM THAT WE HAD HAD WAS DUE TO AN AUTOPLT AILERON SERVO WHICH WAS PROGRESSIVELY TURNING THE ACFT TO THE R. WE WERE INSTRUCTED SEVERAL TIMES THAT WE WERE NOT TO ENGAGE THE AUTOPLT ON THE FERRY FLT BACK. I HAND FLEW THE ACFT FOR THE ENTIRE FLT WITHOUT ANY PROBLEM. I DID NOTICE THAT THE ACFT NEEDED SOME EXCESS R AILERON TRIM; WHICH I DISCUSSED WITH THE CAPT AND THE MAINT CREW ONBOARD. EVERYTHING ELSE WAS NORMAL.