THE PILOT REPORTED TO ATC THAT HE WAS EXPERIENCING SEVERE ENGINE TROUBLE; WITH THE ENGINE RUNNING ROUGH LIKE IT WAS STARVING FOR FUEL. WRECKAGE WAS FOUND IN AN OPEN FIELD; THERE WAS A TREE 500 FT FROM THE WRECKAGE SHOWING IMPACT DAMAGE. A SYNTHETIC SEAL INSIDE THE FUEL INJECTOR SERVO WAS FOUND SEPARATED INTO TWO PIECES WHICH ALLOWED FUEL TO MIGRATE TO THE IMPACT TUBES.