i have 85 baja with a 350 mercruiser. motor only has 4 hours on it. it is running like crap all of a sudden... skipping or something. it will rev and idle fine its only under load. any ideas guys? its the biggest weekend of the year!

Kind of need a little more info, What is skipping the engine or the drive/prop? When is it doing it and what [RPM]? What does it sound like?

I would start with checking the timng and if you have a fuel/water seperator change it out with a new one, or atleast dump it out and reinstall it. Be sure to fill it up with fresh gas before you put it back on though, if you don't it will be a pain to get it to prime.