Pulled my plugs, 2 cylinders look lean?

[Project240]

So yeah, spark plugs from cylinders 1 and 2 look fine, the plugs from the rear 2 cylinders are as white as can be

I'm a little bit foggy on interpreting injector deposits, but white=running lean? (Or detonation, not 100% sure which) Either way, my first thought points toward dirty/clogged injectors on cylinders 3 and 4...if that's the case, would some good injector cleaner probably do the trick? Or would I need to pull the injectors from the rail?

Or am I faced with a different problem entirely?

[Project240]

Anyone?

[Project240]

*sigh*