I got my '97 4.6 HSE at the start of the year, it has 100,000 miles. Heater O-rings fail-wetting the right-hand side of the transmission tunnel carpet. Makes the inside steam up, too. Cheap O-rings but hours to get at them.
Air suspension units are relatively cheap to fix (easier than conventional coils). I get 15--ish mpg (drops to 6 on short run!)
DON't disconnect battery unless you need to. You'll get loads of beeps to reset the Windows, sunroof etc.
You'll hear the pump replenishing the brake accumulator cycling about every 4-7 pedal depressions-annoying but ok.
The lower tailgate bottoms suffer from corrosion of the aluminium skin.
You should get two keys. Check on the back to see what number they are-you can get keys 1-4. 1&2 can automatically recall the mirror/seat memory settings. You can't pair two of the same number keys simultaneously (I have two Key 4s, that's how I found out....) replacements are hideously pricey.
Heater blend motors control distribution and temp of the heating/AC-are suspect. You can check and renew when you dismantle the dash to do the O-rings...
Door mirror auto-dip functions sometimes don't.
Check any sunroof works before you buy-no use finding out it sticks open once you've gone home.
Heated seats suffer broken elements.
Download the RAVE manual from this forum.
That's what I've found out so far.
Keep up on here as there's some seriously well-informed folks here.