DC, drop that thing like a hot potato and walk away.. After 90,000 on my
truck. I have changed the tranny fluid once, the differential fluid once,
the fuel filter 6 times, and put a bottle of Chevron Fuel System Cleaner in
about every 6,000 mi. You can never do too much maintenance on a truck,
especially an 02 with 90,000 on it. He should have already changed that auto
fluid about 30,000 ago. Also, an alignment every couple of years also isnt a
bad thing. Most tire companies recommend every 12months, but I do mine every
2yrs, or when it starts to pull. The other thing is, have them lower ball
joints checked out specifically. I have already had to replace one, and
gettin ready to do the other one when it warms up. Also, look real good for
leaks under the hood and around the oil pan. I have 90k on my truck and it
already leaks there. Plus, that air filter has probably starved the engine
of air a time or two.. Its your choice, but I wouldnt..

It depends on the overall condition of the truck otherwise.  For example, if
he didn't change the air filter or fuel filter, I don't think it would do
any harm, and changing them should restore full performance.  The
transmission is probably not an issue either.  I'm a firm believer in
regular trans maintenance, but part of the equation is what kind of usage
the truck has received.  Pull the dipstick, and check the transmission
fluid.  If it's still pink and doesn't smell burned, then there's most
likely no harm done.  If he's been hard on the tranny, i.e. he's towed with
it or otherwise driven it hard, you should be able to tell by the condition
of the fluid.

In some ways, I'd almost prefer unchanged tranny fluid at 90k.  Think of it
this way, if he had dogged the truck, and just last week changed the fluid,
you wouldn't be able to tell because the fluid would look perfect.  As it
is, you should be able to judge the overall condition of the transmission by
the condition of the fluid.

Of course, if you buy the truck, drop the pan and change the filter and
fluid as soon as you buy it.  You might even be able to negotiate the price
down since you're going to have to replace fluids and filters right away.

CJB

Your first question should be, which services have been missed by 90,000
miles.  I don't think you will find "the other lack of service" actually
amounts to much.  The most critical issue, the oil has been taken care of.
Not changing air and fuel filters (unless they have had a structural
failure) does no damage per se, other than possibly temporarily effecting
performance.  Since I only drive manual transmissions, I can speak to the
automatic transmission maintenance issues.

My wife drives a '99 V-6 5-speed manual Camry, (Thank you, Ford for pissing
me off, or I never would have bought it) with over 120,000 miles.  This car
has only had oil and filters changed since new (I bought it new with 7 miles
on it).  At 105,000 I changed the timing belt (recommended at 60,000-90,000)
it was in great shape when I took it out of service.  It is on it's second
set of tires, the first some horrible factory supplied Dunlop's, the second
Goodyear aqua treads (drove like a new car with better tires).  The brakes
are still original and not in need of service yet (I check them every 3000
miles while changing the oil and rotating the tires).  Needless to say, this
car is NOT driven hard.  Other than the usual squeaks and noises, this car
runs drives handles and stops exceptionally well, and is in perfect working
order.  If I were shopping used trucks, I would much rather the truck be
unmolested than worked on by incompetents.

Good Luck