Possibility of R&R of rubber coupler at # 5 intake runner on a 74
 

I have determined that the rubber coupler at #5 is cracked. I am not too keen on replacing all of the other couplers now just want to keep it on the road til the cold hits.
Is it possible to remove and replace this coupler leaving everything else in place?
Do I need to un-do the injector if so? Any help is greatly appreciated

Not #5 by itself. You would need to remove the one in front of it, which means removing the nuts on all of the runners, and the stay brackets for air box. Then you could try and muscle it out, by then you may as well remove the CIS system.

I'd say it depends on the condition of other couplers and your own fortitude.

Meaning it is rather tough but can be accomplished. If old couplers are sort of dry rotted/cracked they might just fall apart.

I used a hair dryer to warm up couplers and was able to remove runners without damaging them. I didn't remove airbox/manifold stays, but that would've helped I'm sure. I used WD40 and a small hook tool to help on reinstall.

If you've ever installed carbs on any 70-80s motorcycle with factory airbox you'll know what I mean.