1996-2005 Suzuki DF40, DF50 Four Stroke Outboard Service Manual, Page 41Get this manual
2-15 PERIODIC MAINTENANCE (9) Release pinch, allowing air to the IAC valve, and recheck if engine speed is stable at 800 900min
NOTE: The idlingtrolling speed of 800 900minis controlled by the IACidle air controlsystemIf the engine speed does not return to specification, the IAC passage (including the IAC hose and silencer) may be clogged or the IAC system may not operating correctlySee the "IDLE AIR CONTROL SYSTEM" section, 3-20NOTE: Trolling speed (in-gear idle speed) is the same as idle speed(10) Reinstall parts removed earlier