Bob.
All 4-strokes will gain some oil, so depending on temperatures and speeds, as well as number of hours since the last change, it's not unusual to have the crankcase level rise. If the oil gets diluted with fuel, it's very thin and reeks of gas, so you probably don't have a blown pump. Most bad pumps will reveal the leak if they are removed from the motor, and connected to the fuel line, then primed with the bulb. If fuel leaks out at the pump push rod, it's shot. (diagnose before replacing parts).
A high-speed miss could be either fuel or ignition (or mechanical), so start by changing plugs, and inspecting the old ones... easy, cheap, and needs to be done from time to time anyway. Diagnosing the appearance of plugs tells a LOT about the motor.
The 9.8 should be quiet. Identical to the merc. You can check valve lash (almost never out of adjustment), as that could cause a miss and also could cause it to be louder.
Most carb issues are at low speeds, unless some jackass installed the wrong (8 hp) main jet in the carb. Yes, it has been done...Contamination in the fuel can cause missing, as could a thermostat that is stuck open... that would also contribute to gaining oil. An IR thermometer should show a running block temp of around 150 degrees (but different areas will have different temps). If way below that, the stat might be stuck open.
