THE ACFT LOST POWER DURING INITIAL CLIMB AND CRASHED ON A RESIDENTIAL STREET DURING AN ATTEMPTED FORCED LANDING. THE THROTTLE ARM WAS FOUND SEPARATED FROM THE THROTTLE SHAFT. THE ARM HAD BEEN REPLACED 19 HOURS PRIOR TO THE ACCIDENT. EXAMINATION OF THE CARBURETOR REVEALED THAT THE SHAFT BUSHING WAS WORN AND LOOSE AND THAT THE JAWS OF THE NEW ARM WERE CLOSED COMPLETELY BUT PRODUCING NO CLAMPING ACTION. SUBSEQUENT TESTS OF THE ARM AND SHAFT REVEALED THAT THE ARM WOULD SLIP EASILY ON AND OFF THE SHAFT. TESTS ALSO ESTABLISHED THAT THE RECOMMENDED METHOD OF SAFETY WIRING THE ARM TO THE SHAFT DID NOT RETAIN THE ARM ON THE SHAFT. THE MAINTENANCE FACILITY DID NOT PERFORM THE FINAL INSPECTION IN ACCORDANCE WITH THEIR OWN FAA APPROVED REPAIR STATION MANUAL. THE MAINTENANCE FACILITY HAD RECOMMENDED A MAJOR CARBURETOR OVERHAUL TO THE PLT/OWNER BUT HE REFUSED BECAUSE OF THE QUOTED PRICE.