SNOW AND ICE CAUSED ENG PROBS.

Narrative

ON A SCHEDULED FLT FROM OTZ TO KIANA THE THROTTLE BECAME STUCK AT 21 INCHES HG. I ELECTED TO RETURN TO OTZ WHERE THE RWY IS MUCH LONGER AND IN BETTER SHAPE. UPON REACHING OTZ; THE VISIBILITY HAD DECREASED TO 3/4 OF A MI. I DECLARED AN EMER AND PROCEEDED INTO THE CLASS E SURFACE AREA. ON DOWNWIND LEG FOR RWY 8; I MANAGED TO BRING THE PWR BACK TO 19 INCHES; AND THEN ON BASE LEG; THE THROTTLE BECAME FREE. I LANDED WITHOUT INCIDENT. ONCE ON THE RWY; I ATTEMPTED TO TAXI BUT WAS UNABLE DUE TO ENG ROUGHNESS. I SHUT THE ENG DOWN AND HAD THE AIRPLANE TOWED BACK TO THE RAMP. UPON INSPECTION OF THE ENG; THE MECH FOUND AN UNUSUALLY HIGH AMOUNT OF SNOW IN THE AIR FILTER; WHICH WAS THE CAUSE OF THE ENG ROUGHNESS. DURING THE FLT THE WX ENRTE WAS 1 TO 3 MI IN SNOW. SINCE THE TEMPS WERE IN THE 20'S; I BELIEVE THAT THE SNOW WAS BLOWN THROUGH TO THE AIR INTAKE. WHILE GOING TO THE INTAKE IT MELTED TO WATER AND FROZE TO THE FIREWALL; AND IN TURN FROZE THE THROTTLE CABLE IN PLACE. SINCE THE SNOW WAS VERY WET; IT MANAGED TO CLOG THE AIR INTAKE.