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2005 Yamaha F90. Fuel injection. I have changed oil, lower unit oil, waterpump, thermostat, Fuel filter and plugs. Purchased the boat ran fine, but has obviously been sitting a long time. 69hrs on engine. Pretty solid when throttle is up. At Idle the rpm's are jumping between 625-800. Missing and jumping. No fouled plugs. Could it be bad gas? I did put the ethanol treatment in when I filled it up. Any other filters I need to change? I have the diagnostic tool. I tested the IAC. Kinda confused on how to run that test. With the motor running, I did the fully open test and it shut the motor off. Would that mean the IAC is bad?