I am only at rank 97%
I saved my game just before POINT OF NO RETURN
I have gotten all the brains and figments, cobwebs, and baggage in all the worlds.
I know this because each door in the collective unconscious has pictures that light up when you get all the figments, cobwebs, and baggage for each mind.
I think I have all the PSI Cards for each area of the game and all the PSI Challenge Markers too.
I also found all the Scavenger Hunt items and got both rewards.

I have 6 PSI Cards and 7 PSI Cores.
Am I missing something?

SPOILERS:

There are more figments and (PSI cards, too, I think) to gather once you go past the Point of No Return. There's a fortune teller next to the first tent you have to enter who will redeem any items that need redeeming in exchange for an increase in ranking. Later on, you can come back to this point using the teleporter animal.
From what I can recall, there's mainly figments ahead from this point.

I know that you can't go back to camp after this point.
I think I got all the PSI cards and PSI Chalenge Marks in all areas around the camp and asylum.
I know there are 94 figments and 3 cobwebs in the last mental world.
You need 100 figments to go up a rank there are only 94 figments.
I have 6 cards and the 3 cobwebs in the last mental world will give me 9 cards total enough to go to rank 98.
Is there anything I am missing to get a higher rank either at camp or in the mental worlds?

Remember that a lot of figments may be worth more than 1 point and you only need 100 points to go up a rank, so after collecting all 94 figments, you may go up 2 ranks instead of just one.

EDIT
Sorry, the american date format confused me, didn't realise how old this was :p