A somewhat minor but aggravating problem I am having with this outboard. To be clear it is a 1995 Mariner 225 Magnum EFI 2 stroke. Engine runs great other than at idle. compression checks have been done and range from 100-105 on all six. Boat planes fine and is very responsive. My question is about some rough idling. When in gear and leaving no wake zones, it frequently coughs and sputters and often dies. RPMs at idle in gear are around 550-600 per dash gauge. Plugs were changed and only run quicksilver oil and non ethanol gas. Is adjusting the idle speed on this engine as simple as adjusting the throttle linkage on the hot foot? I feel if it was idling around 600-650(what I'm finding in the manuals) it would purr at idle. Other boaters tell me that a big 2 stroke just doesn't idle good and accept it. I am a type A perfectionist so I choose to investigate. I'd like to get some opinions/advice on here. Thanks in advance!