You're right on the foam, but as I discovered, when mine started to sag, the factory foam had disintegrated.

I shot a little Great Stuff in the sagging areas and put it back up before the foam set up. I used the type that doesn't expand much as it dries.

87 Montero, bought new, by me -
88/89 intercooled Starion Turbo engine-
with awesome audio.