Buying advice on 2004 Grand-Cherokee...

[lord Kelvin]

I've never owned a Jeep, so I'm looking for some quick advice.

My neighbor has a '04 Grand-Cherokee that I can buy for $5500...the trade-in price from the dealer. I need to give an answer this afternoon.
Here are the specifics:
-136Kmiles
-8cyl engine
-Special Edition version with leather
-4WD
-never in an accident
-religiously changed oil/fluids/filters etc.
-needs a TPS sensor per amateur mechanic with scan tool

It's been a very reliable car for him until the TPS sensor went last week. Guess I'm wondering how long I can expect this vehicle to go before it starts needing costly repairs? Also, what is the weak link on these vehicles....the parts that fail first?

I appreciate any advice you guys can give.
-Lord Kelvin.

NOTE: I have done virtually all my own car repairs for the last 20yrs so I will probably do all the maintenance on this.