It's a late 90s Merc 225hp 3.0L EFI - Ran the engine on the water yesterday for the first time, runs great except for at idle it will hiccup or stutter a little bit...Happens usually when putting the shifter into neutral from forward or reverse, like it is going to stall out when I put it into neutral...Mostly annoying when coming into the dock or trailer as you get in and out of neutral the engine stutters and rpms drop but never stalls out. Hope I am making sense... What do you think can cause that issue?