You don't need to.
Swap injector 4 for injector 3, clear the code and start again.
Or unplug injector 4 and make sure the engine doesn't change what it's doing, then switch it with 3 and see if the problem then does the same thing on 3.
These means you don't need to disturb the inlets first until you need to check leads.
I've got 4 spare coil packs here too, and a set of leads. But try injectors first.