250hp 0X 66 running rough

[yamytec7]

Hi there , Ive got this 250 OX 66 and she will run great and then suddenly start running rough , Ive checked the fuel and its clean .There seems to be excess oil coming outta the intake and when it was in the water there was an oil and fuel slick on the water . The plugs had a bit of carbon and were wet , Ive checked the 3 ful pumps and they are fine . I pulled the intake and inspected the reed valves and nothing there , Any ideas ?

[99yam40]

monitor spark,timing, and fuel pressures to see if something is changing when problem shows up