The 318/360 design dates from about 1967; the 360 itself showed up in the early seventies.
These have always been extremely stout engines, generally outlasting any comparable Ford or Chevy, needing only rings and valve job to go yet another 150k. The 318 is overmatched by the weight of the vehicle compared to the more ordinary, lighter trucks of that earlier era. The 360 is the ideal motor.
As to horsepower, so what? It's only a derivative of torque, and that is the only thing that matters in a truck. Where it peaks in the rpm band, and how well the truck is geared/tire-matched is what matters. The 360 is just fine.
The intake manifold gasket is, as mentioned, a problem. Plenty of quality aftermarket fixes (APS PRECISION, HUGHES ENGINES among others) and the factory has issued a revised, higher quality replacement.
The transmission, a late variant of the 727 3-speed, is also a stout piece when properly maintained. Chryslers' design was superior to the GM and FORD autos; get it serviced properly, band adjustment and fluid change annually ; consider a TRANSGO shift kit and a stacked-plate auxiliary cooler plus an auxiliary filter. Use only MOPAR ATF+4 or a high quality synthetic or semisynthetic ATF. (I'm now using SCHAEFFERS 204-Supreme and a MAGNEFINE filter). Many of us leave overdrive off under 50 mph, and I believe that any idling should be done in Neutral (as with wifes JEEP AW-4) so as to have fluid pumping throughout trans. If you rebuild it, then have them go to the 47RH specs (diesel).
I bought one last fall with 86k on it. Used LUBE CONTROL (LC-20) first 6k with dino and BALDWIN B2-HPG. Now on rinse phase of ARX treatment (same filter type and DELO 10W-30); after an LC "Mola-soak".
With new plugs/wires/cap/rotor, idle is glass-smooth at 95k. I fully expect another 100k with no problems. Cooling and HVAC will be gone through this or next season as I believe that any vehicle needs this system overhauled at 6-7 years; plus timing chain will be replaced with best quality aftermarket.
Fuel mileage has been 13+ in-town, and 16+ on highway for this '01 2WD Quadcab, 3.55 with 245/75-16's (though all service has not yet been performed; I'll find additional improvements as I go along as EPA was 13/17 which I fully expect to beat. I'll change from stock exhaust to custom free-flowing -- emissions-legal -- and modify air intake).
As to fuel-related problems, I've been using FUEL POWER (FP-60) and 87-octane gas with no indication of preignition. FP-60 is by far the best, least expensive fuel additive I've ever tried. Truck definitely has more pep than when purchased, and I don't ever have to worry about "bad" gas with FP-60.
DODGETALK and DODGETRUCKS.ORG are decent sites to check for others experiences.
All brands have problems. Just search them out, correct them before they go wrong; plan for other ones and enjoy it, don't worry over it.
I'd be glad to have any quality FORD, DODGE, CHEV truck. Happens that I like Mopar best, but bought the truck because of the fears of others: the mileage (fuel and odo) and thus was able to get an option-loaded problem-free truck for only a little over wholesale auction price. Literally, one-third the new price. (Depreciation? Who cares!? Gas mileage? Completely irrelevant! Do the math.)
I'll go through every system -- systematically -- correcting deficencies, upgrading where indicated, and drive this thing till it has another 100k or health deteriorates just too far.
And as I can't afford -- literally -- to be stranded (health) you can take my experience as a guide: Fix what needs it, plan on reasonable replacement schedule before things break, drive it till it croaks (300k and one tranny if you're careful), and never look back.
And, as other posts have mentioned, there is an enormous wealth of aftermarket upgrades and highly experienced shops dealing with these last of the golden era drivetrains. The latest and greatest is wonderful stuff (whoa, five and six speed autos, OHC engines . . . just don't ask me to foot the repair bill). Could be the 360/727 is the last of the reasonably affordable drivetrains.