Re: Tohatsu 9.8 won't stay running
You likely have either one or both of the following:
1. Incorrectly adjusted idle stop screw.
2. Junk in the low-speed carb circuit.
Are you running a water-separating filter in the fuel line? If so, that should capture any reasonable amount of junk or water that may have been introduced via the fuel tank in so short a period of time.
Has the motor been run, then left shut down for a few weeks without emptying the carb? If so, low-quality fuel may have started to varnish up the low-speed carb circuit.
Since any EP motor requires dealer installation, and you have a 3-year warranty, ask your installing dealer to look at the problem. Of course, if the issue is bad fuel (and junk in the carb passages as a result), that is generally considered abuse -- or at least beyond the control of Tohatsu, and likely will not be covered by warranty.