Hunting Idle on a HPDI 200HP,year2000

[Mr Boat]

Just replaced a head gasket on one side and also replaced felt gaskets on the injectors on the same side. Engine has new spark plugs. All fuel lines, bulb, racor filter and a new 10 micron on engine filter where installed just prior to head gasket replacement. 40 hours back hi pressure filter and VSR filters were replaced. Engine starts and runs fine on garden hose, but idle vascillates between 500 and 600. Motor use to idle smoothly at 600.What is the next step?
Thanks,
John

[mrv8outboard]

Check the tps. How it the engine at wot? What does the software tell you?

[Bad Kitty]

Was the idle stable on the hose or in the water ?

When you run them on the hose there isn't enough back pressure on the exhaust (thru the prop) for them to ilde smooth.