THE ACFT WAS DESCENDED FOR APRX 7 MILES AT LOW POWER & SLOW RATE FOR THE LANDING AT WHITE MARSH ARPT. THE DESCENT STARTED AT 2800 FT & CONTINUED STRAIGHT IN TO RWY 27. AT ABOUT 200 YDS FROM THE RWY & AT 200 FT AGL THE PLT DECIDED HE NEEDED POWER TO LAND PROPERLY. AS THE THROTTLE WAS APPLIED THE ENG SPUTTERED & COUGHED, ACCORDING TO THE PLT, BEFORE QUITTING. THE PLT THEN TURNED THE ACFT TO THE LEFT TO LINE UP WITH I-95 SOUTH BOUND. A TRUCK INTERFERED WITH THE HIGHWAY LANDING & THE PLT BANKED THE ACFT TO THE RT TO LAND ON THE GRADED 40 FT WIDE SHOULDER OF THE INTERSTATE. THE ACFT HIT TREES & GROUND LOOPED TO A STOP. THE PLT STATED IN HIS REPORT THAT OVER PHILLIPS AFB HE NOTICED THAT THE FUEL GAGES WERE READING 5 GALS EACH & BOUNCING AROUND. HE SAID HE FELT THAT CARB ICE OR MAG FAILURE WERE CAUSAL, AND HE RAN OUT OF TIME TO GO THRU ANY EMERGENCY PROCEDURES (AS HE DID NOT BECOME AWARE OF A NEED FOR ACTION UNTIL THE APPLICATION OF THROTTLE AT 200 FT AGL ON FINAL APPROACH).