The main problem with the 3.0's is the tendancy to burn the #5 and #6 exhaust valves. As far as the HG, according to Toyota not all the 3.0's had the problem, it was only those series of engines from certain plants. I was told this by my local dealer when inquiring about my 3.0. To make sure I wasn't getting a line of crap, I called a couple other dealers in the area, and they all said the same thing, my Vin# wasn't from the production series that had HG problems. The burnt valve issue does arise from time to time(I have had 2 within 6 yrs), but it isn't bad if you have mechanical abilities and another rig while it is down.
As to power to weight ratio, the 3.0 is better for something like the 1st gen runner, or the 2nd X-cab's. The 3.0 in an auto is gutless, but then again so is the 22re(unless it is a turbo. On average, the 22re gets 2 mpg's more than the 3.0 fo the same type of vehicle w/5 spd. The trade off for more power is less mpg as is the case with any larger engine. My '90 x-cab with the 3.0 averages about 15-17 city(depending on how heavy of foot I use), and as well as 19-21 on the highway(get 23-24 when out of state). It used to do better, but we have so much crap in our ghas here in CA, that mileage has dropped of a few mpg's. The mpg isn't bad considering all of the extra drag I have, i.e., kc lights, roof rack. larger tires, bumper, and it weighs 1k lbs over stock. When loaded for long wheeling trips, the rig weighs in at just over 5200 lbs w/gear and passengers. With it weighing this much, I still get 17-19 on the highway and can climb the Sierra's at 70 mph or better. I have friends that have the 22re's in both trucks and 4-runners with gears/tires to match, and none of them can keep up.
I think most of those that hate their 3.0's either had it with the auto tranny, larger tires and stock gears, or were expecting something like the power of the Chevy 4.3, which didn't come along until later. I am quite happy with my 3.0 and the mod's that I have done to the engine(ignition, headers, cold air intake, etc.) have worked well, not huge power gains, but noticeable. I have owned it since it was new, and I still get the same mpg 15 yrs later as it did when it was new, eventhough it weighs more has more drag.
The best person to decide between a 22re and a 3.0 1st gen Runner is you. I would drive them both and see what one you like better, which one fits your driving style.
