I just got this Kawasaki zxi 750 a couple months ago and it has been sitting for about 6 years with low hours. Gas lines were dry and it would not start. I replaced the fuel filter battery, ignition relay, the volatage regulator and the, trim motor. All were badly coroded. I put gas in the tank and after all that it started. I added a line for a garden hose to be connected. And it starts up right away now. But that brings me to my issue I can not figure out. I'm new to jets skis so I've learned everything off videos on the internet on how to fix stuff, but when I run the jet ski for about 2 min it runs fine but as soon as it runs for a little the idle starts like pulsating and I shut it off because I don't want it to damage anything. And also the battery doesn't seem to be holding a charge and the water coming out of the exhaust is dark water I just want to know if that's normal and not oil. So if anyone could help me with my problem that would be greatly appreciated I'm at a stand still. And also what other stuff I should check out before running it on the water just so I won't have problems on the water. Sorry for all the questions