Looking at a 28 ft. pontoon boat with 100 Evinrude engine. This is a 1989 model , one owner, 370 hours on engine and boat. I have a 2005  8 cylinder Jeep Grand Cherokee Laredo, how well will the Jeep pull this pontoon?

Should be good on power, might sway a little.

What's it weigh?

We tow a 28 foot tritoon behind a VW Touareg. V6 turbo diesel. Does fine, don't even know its back there... well, that's not really true because the damn thing is like 10 feet high from ground to top of the playpen. But, we cannot tell it is back there for accelerating or braking. We have a built-in brake controller and self-leveling rear suspension. Don't know what your Jeep has but I would seriously consider having brakes on the trailer.

Well. bought the pontoon today, it turned out to be a 25ft. It;s been sitting in the lake for a year. When I bring it home what do you all suggests I clean the pontoons with? P.S. sucker hadn"t been started in 7 months, same old gas and it cranked up on second turn of key. Took it for a test drive for two miles and it did fine.

Get rid of that old gas. It will kill an engine. Have you power washed the pontoons yet? After power washing, look for any pinholes along the water line.
"Toon-Brite" works pretty good on lightly tarnished 'toons. Heavily corroded or calcified 'toons require something harsher, like muriatic acid.

Goin to paint engine. Can't find paint color for 89 Johnson GT 100 ( It isn't white. kinda charcoal grey color). Also, what kind of primer should I use on the lower unit and cowling? Any suggestions on how to go about the process , do's and don'ts.