EMER GND EQUIP CALLED OUT FOR SMA WITH ENG PROB IN A NIGHT OP.

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DURING DSCNT FROM 6500 FT TO PATTERN ALT; PASSING THROUGH 3800 FT AT APPROX A 300 FPM DSCNT; THE ENG STARTED RUNNING ROUGH. I IMMEDIATELY PITCHED FOR BEST GLIDE; WENT THROUGH EMER CHKLIST; MIXTURE RICH; FULL THROTTLE; MAGNETOS BOTH; ETC. ENG PWR WAS INTERMITTENT; AS IF LOW FUEL. FUEL WAS MORE THAN ADEQUATE; HOWEVER; WITH ABOUT 20 GALLONS LEFT AT DEST. ENG RPM DROPPED BY ABOUT 200; BUT I CONTINUED ON TO MAKE THE FIELD. SYRACUSE WAS MY DEST. I DECIDED NOT TO DO A MAGNETO CHK MID-AIR AS I WAS SO CLOSE TO THE ARPT AND DID NOT WANT TO RISK SHUTTING DOWN THE ENG. I ASKED APCH CTL FOR A SHORT APCH WHICH WAS APPROVED. HE ASKED IF I WANTED THE EMER EQUIP. RECEDING TO MANY NTSB RPTS ABOUT PROUD; INVULNERABLE PLTS; I SAID SURE; GET THE TRUCKS. I LANDED SAFELY AND PARKED THE AIRPLANE. I MADE A RPT TO THE ATC SUPVR AND TO ROCHESTER FSDO THE FOLLOWING DAY. AT THE MAINT FBO THEY REMOVED 8 FOULED (BADLY FOULED) PLUGS; AND RESET THE MIXTURE CTL; WHICH WAS THE SOURCE OF THE PROB. (PS: I LEANED AT ALT AS BEST AS I COULD). THE MIXTURE WAS WAY RICH PRIOR TO THIS MAINT. ON THE GND; THE ENG WAS REAL ROUGH; AIRPLANE SHAKING DURING THE MAGNETO CHK; WITH A 200-250 RPM DROP. THE MECH NOTED THAT TIGERS ARE NOTORIOUS FOR RUNNING RICH AND FOULING. IT WAS QUITE A DISTURBING EXPERIENCE WITH THE THOUGHT OF NOT MAKING THE FIELD AND NOT HAVING A SUITABLE LNDG SITE; OVER A CITY AT NIGHT. I WAS ALERT HOWEVER; CALM; AND TOOK THE NECESSARY ACTIONS; IE: FUEL PUMP ON; MIXTURE ADJUSTMENT; BEST GLIDE; SHORT APCH; ETC. THERE WERE NO CONTRIBUTION OF HUMAN FACTORS; IE; FATIGUE; ETC.