Narrative:

Possible carburetor icing due to possible water in fuel caused engine to lose power intermittently. Emergency was declared and march AFB approved landing. More time between fueling and sampling of fuel may have prevented occurrence.

Google
 

Original NASA ASRS Text

Title: A C150 PLT EXPERIENCED A ROUGH RUNNING ENG AND MADE AN EMER LNDG AT A MIL BASE, RIV.

Narrative: POSSIBLE CARB ICING DUE TO POSSIBLE WATER IN FUEL CAUSED ENG TO LOSE PWR INTERMITTENTLY. EMER WAS DECLARED AND MARCH AFB APPROVED LNDG. MORE TIME BTWN FUELING AND SAMPLING OF FUEL MAY HAVE PREVENTED OCCURRENCE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.