By shot-gun I'm refering to replacement without testing and yes, all three should be shot-gunned.
If you can replace the sparkplugs, you can shot-gun these connectors. Testing/evaluating is more difficult. The logic behind shot-gunning these connectors is largely based upon the concept that testing is more expensive than the replacement unless one can do the testing one's self.
Bosch Master, ASE Master, L1
33 years MB technician