I bought my 88 Jeep Comanche Pioneer (4.0L 6 Cylinder) in 1992, and when I bought it, it had a little over 100,000 miles on it. I have put another 100,000 on it in the years since, and have had no major engine problems.
I have had the radiator replaced once (Original one was plastic type, replaced with metal type that can be rebuilt.)
My sore spot with this vehicle (Manual 5-Speed transmission) is the slave cylinder of the clutch, which requires a transmission removal, and replacement of the clutch plate at the same time. I've had to have it replaced about 4 times during my ownership of the vehicle, and I'm not a young hot-rodding type of person - I'm in my sixties and now retired.
It has had several other problems, but in its' 200,000 plus miles, never had any major engine problem.
All considered, I think this is the best vehicle I have owned - I even talked my wife into purchasing a 1999 Jeep Cherokee Laredo, which she has been very happy with as well.
If I had to do it all over again - I'd still buy it. It's been a very reliable vehicle for me.
Bought my 88 Comanche back in 1990.
Seems like I've replaced just about every part in it except for the engine. The vehicle is coming up to 500,000 kms.
My biggest complaint is the electrical system. I've replaced the headlight switch a couple of times. I decided to put in a universal switch I got from Cdn Tire. No more problems there. As usual it's the heater circuits blowing out. I'm going to try a separate switch and relay to the blower hopefully that'll cure that problem that's been around for quite few years.
All in all, I don't recall the Comanche ever leaving me stranded, but there been some real close calls.