My Jeep called (grunt) has been the only vehicle that I have owned over 5 years. It is a vehicle that does require maintenance for some leaks and some general items, but I can tell you it has always got me down off the mountain.
Paint is still good on the roof and sides of the vehicle, no rust on the vehicle (yes we live in Canada), but on the hood of the truck the paint has thinned out, but we are changing that this spring with a performance addition for the K&N system.
Does have a cooling problem; we tow a off road tent trailer, which is 3,000 pounds loaded up, so there are some current issues there.
New radiator was put in with hoses. I do have a problem with pressurization of the cooling system, and have gone through a couple of radiator caps.
Moved the electric fan control to inside the cab of the Jeep, so it's now a manual switch which allows me to control a little more when "I" think extra cooling is needed. It has worked well.
Jeep Cherokee's have a problem with heat.. there is no doubt with that, and has been our focus to solve for towing during the summer, or actually fishing season period.
Watch your thermostat, make sure it is working well. We have cut two holes towards the back of the jeep hood, and covered with a nice vented plastic for heat to come out, headers are wrapped as well for less heat inside the engine compartment. Added super cool additive used on the drag strip to the coolant, this has helped substantially. Additional cooler added for transmission. We are putting in new gears for towing as we are a little out and need to drop the ratio. It's just common sense.
As for power, the 4.0 H.O. is about torque. I can tell you the K&N cold intake system has worked well, amongst other things done) not all listed here. I chose to use a spacer for the injection system, there is a difference, but you will have to decide where you want the power, I chose mid range. Please don't fall for systems that say they will give you "turbo" power.
We have changed the spark plus assemble to Low ohm, however there is no performance available, and my own humble knowledge for a distributor system that will match that. I keep "grunt" our Jeep well maintained, and with all the crap I have inside the Cherokee (yes I am a button and switch guy) 0 to 60 is 7.1 seconds... yes my father doesn't believe it either (muscle car guy), try it 13 times on a good day. Numbers don't lie, and honestly.. not a super number, but good for a Cherokee.
Cherokees are not racers, they work hard and they do pull.. just don't expect something that is beyond what it can do.. if you are a fisherman like me, use low range and fix your heating issues when going up a mountain.. as I said, it has never let me down, we love the truck and with a new baby on the way, there is no new vehicle that we would buy, this one has gone over the Coquihalla so many times, and we know it gets me back home every time.
As for the fuel, did you really buy a Cherokee for fuel mileage? Keep it under 100 km per hour if you want to save fuel and your foot off the gas. Hard to do with a intake system :)
It looks like a coffin, mine easily roasts the back tires (30's deep dish), a couple of imports left behind, and one Ford and GM truck (for the record the Ford was only by half a hood length).
The seats are uncomfortable after 4 hours.
It's a good truck to learn basic maintenance and leaks (if you don't want those, then don't buy it or learn how to fix them, it's not that hard a good father and son project, or mom and son project), but the truck will always get you home.
I love vehicles, owned a lot, changed every year.. this one, I have had for five years, and as much as people have asked to buy it.. I just can't do it.. Love the Jeep, and the fun... cheers.