This is on that 9.8A3? Fuel ratio is fixed. The 2 carb gaskets should have a plastic spacer between them. What do the plugs look like? I take it they are NGK DCPR6E plugs...
The 9.8A2 and A3 (you didn't say which model -- year is irrelevant) have an exciter, a pulser, and a CD. Any one could be failing hot. The exciter and pulser can be tested with an ohm meter.