Alright, the consensus sounds like I should start with an impeller
replacement. Will do, especially since it sounds like a maintenance
item anyway. If that doesn't work, I'll start looking for other
restrictions in the cooling system. Just to clarify, when I say
overheating, I mean that the temp gauge was pegged and the exhaust
smells of burning oil. The gauge goes up to 240 I believe (I'm not on
the boat right now). When I would rev it and get it to cool down, it
would get down to about 160-180. I have no idea when it was last
replaced so it may have been about dead anyway. I will replace the
thermostat with a new one too instead of putting the old one back in.
It looks just like a standard auto thermostat. Is there any
difference? In other words can I pick one up at Autozone or do I need
to find a Mercruiser parts dealer?

As far as the rewiring goes, I am going to get started on that too.
My horn doesn't work because of a faulty switch and my tilt/trim has
problems in the up direction. I have to jack around with the switch
to get it to go up, not good. That could be a weak pump I guess but I
would imagine that up and down work on the same pump through a
birdirectional valve. Am I right? I guess it could be a solenoid on
the valve if that is how it works. Any advise on that one?

Back on the impeller, I am pretty good with wrenches and I have a
decent shop and I'm not scared to do it myself. I've heard that I
need to take the outdrive almost completely off to get to the
impeller. Can I get the basic steps from someone who has done this?

Thanks for all of your help. The internet is a wonderful thing.

Chris