People in my party in Fallout 1 have crippled limbs and only run away when we get into a fight. Is there anyway to heal them? Is there some sort of doctor I can visit. Two out of my three NPCs are completely useless (although they're still good pack mules) and it's really annoying.

just using doctor skill is often not enough. tis better to combine it with using (a.k.a putting it in your fast-slot and pressing it) doctor's bag. or you can visit official doctors like morbid in the junktown or his apprentice in the shady sands.

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Another way to use the doctors bag without doing the above, right-click to get the arrow and left-click the NPC and hold down the mouse button, go down to the backpack and let go of the mousebutton. (now you'll see your inventory and clicking the doctors bag in it will make you use it on the NPC)
Like mentioned, you'll need to use the doctors skill to fix crippled limbs, first aid won't do anything about those.