Unfortunately, I didn't make it out this weekend. Glad to hear it resolved the issue on your motor. Just curious, where did did you get your IAC...online or local shop?

Bought the IAC from BAM Marine in Florida.. (www.mercruiserparts.com).

Got out this weekend and everything ran perfect. No issues at all at idle. So, I'm guessing cleaning up the IAC resolved the issue. I'm going to give it a few more outings before I'm convinced, but so far it is looking good. Thanks for all suggestions.

One year later update. ..no issues until last weekend, same symptoms came back. Installed a new iac with no help. Checked for codes, none. Installed some spark checkers on the even cylinders and found #8 not firing. My hand happened to touch the wires on the plug that connects right above the ignition modules and everything returned to normal. Further investigation revealed that one if the four wires on the plug was really flimsy and had somehow broken internally. I'm assuming that's the wire that connects to the 5 and 8 ignition module. Repaired the wire and ran it for the lasy three days with no issues.