If it's an 07 Merc 9.9, it's really a Tohatsu 9.8 with slightly different carb, and possibly slightly different shift coupled to throttle. What is the actual symptom? There is an exciter and pulser as well as a siamese ign coil. You can check the exciter and pulser for both DVA and ohms. There also ohm tests for the CD, but your analog ohm meter MUST be below 9v (3v is OK) or you may cook the CD. Tohatsu has a great Factory service manual for it, also available in Nissan version; same price:
Covers 8A3 & 9.8A3 4-stroke models
Part #: 003-21056-1
List Price (MSRP): $41.67