B737-300 ACFT STICK SHAKERS ACTIVATED AT CRUISE ALTITUDE. ALL INDICATIONS NORMAL. C/B'S PULLED.

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CRUISING AT FL360; PLT'S STICK SHAKER ACTIVATED. ACFT CONFIGN AT THE TIME WAS AUTOPLT AND AUTOTHROTTLES ENGAGED WITH LNAV AND VNAV SELECTED. I GRABBED THE CTLS AND CLICKED OFF THE AUTOTHROTTLES; SCANNED THE CAPT'S AND STANDBY AIRSPD INDICATOR AND COMPARED TO MINE. ALL 3 INDICATED 250 KIAS. STICK SHAKER WAS STILL ACTIVE. I CLICKED OFF THE AUTOPLT AND HAND FLEW THE ACFT. STICK SHAKER STILL ACTIVE. ENG INST AND PRESSURIZATION WERE ALL WITHIN NORMAL LIMITS. I CONTINUED TO FLY THE ACFT AND HANDLED THE RADIOS AS THE CAPT CONTACTED MAINT CTL AND DISPATCH. MAINT CTL HAD THE CAPT PULL CIRCUIT BREAKERS D-8 AND D-9 ON PANEL P-18-2. CIRCUIT BREAKERS SILENCED STICK SHAKER. CONTINUED TO ZZZ TO AN UNEVENTFUL LNDG. SUPPLEMENTAL INFO FROM ACN 754951: I HAVE SEEN A DECLINE IN THE QUALITY OF OUR MAINT THE LAST FEW YRS. FLEW THIS PLANE LAST NIGHT AND HYD VALVE FOR A SYS WAS INOP. ON THE OVERNIGHT THEY SAID THEY FIXED IT AND ON PUSHBACK A SYS ROSE TO 600 LBS AGAIN JUST LIKE NOTHING WAS FIXED AND HAD TO CALL MAINT CTL AGAIN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED HE AND THE CAPTAIN WERE BOTH QUITE SURPRISED WHEN THE CAPT'S STICK SHAKER WENT OFF FIRST FOLLOWED BY HIS COLUMN SHAKING. WITH AIRSPEED AND ANGLE OF ATTACK INDICATIONS NORMAL AND ENGINE INSTRUMENTS AND CABIN PRESSURIZATION OK; THEY LOOKED TO SILENCE THE STICK SHAKERS. MAINT CONTROL DIRECTED CAPT TO PULL THE TWO C/B'S. REPORTER DOES NOT KNOW WHAT CONTRIBUTED TO THE ERRANT INPUT THAT CAUSED THE SHAKER TO ACTIVATE. THEIR PREFLIGHT REQUIRES THEM TO DO A STALL WARNING TEST USING THE TWO TEST SWITCHES ON THE AFT OVERHEAD PANEL AND SYSTEM TESTED NORMAL. REPORTER ALSO NOTED THE DECLINE IN THE QUALITY OF MAINT OVER THE YEARS. THE INBOUND FLIGHT THEY FLEW; PRIOR TO THE STICK SHAKER INCIDENT; HAD A PROBLEM WITH THE 'A' HYD SYSTEM NOT DEPRESSURIZING DURING #1 ENGINE START. MAINT SAID THEY HAD FIXED THE PROBLEM; ONLY TO FIND OUT THE 'A' SYSTEM STILL DID NOT DEPRESSURIZE.