hiya jimo and Blindboy,

You may want to look over the wiring diagrams for your 1996 Volvo 960:

http://www.volvowiringdiagrams.com/?dir=volvo/960%20Wiring%20Diagrams

For the 1996 960 diagram, see page 15 for a diagram for the ignition coil to ignition control module connection and assignment.

Appears Motronic power stage 1 controls coils for cylinders 1, 3, 5.

and ...

Appears Motronic power stage 2 controls coils for cylinders 2, 4, 6/

Both power stages are at the left side of engine, near intake manifold, so sayeth the diagram).

Like blindboy says here, it would not hurt to treat the wire harness connectors to the power stage modules an inspection for dirt, corrosion, and treatment with, well, DeoxIT or a dielectric grease. As well as check the connection to ground for both modules. Diagram shows the ground and describes location.

Also, you have cleaned the positive crankcase ventilation (PCV) system, yes? If using regular (not synthetic) oil in your Volvo 960 B6304 engine, a clogged PCV, among other items, can enhance fouling spark plugs.

Ensure spark plugs are at a proper gap. Yet what kind is the best spark plug for your 960? Well, something to research for you. You can start with the mighty, if wonderful:

https://www.brickboard.com/FAQ/700-900/

And search this forum using the search feature. You probably already know that.

(Trying to get facebook Volvo owner uses to use the brickboard.com)

Questions?

Hope that helps.

B.
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Jonathan Harshman Winters III: The Mightiest, Greatest, & Most Powerful North American Comedian & Comedic Actor in Perpetuity