merc 210 slow top speed

[00 challenger]

I have a rebuilt 210 sport jet on a 2000 challenger 2000 and it has been running great all summer recently it wont go over 4000 Rpms and cant even pull a skier out of the water. Wondering where to start. some times it wont restart right away after i shut it off.

 

[igneous]

Start simple....compression test, batt voltage under load, fuel filters/delivery system. May also want to check plugs, filters, etc. Need specifics on engine behavior...could be a sensor.