Mine has been very reliable. Only major part replaced other than the timing belt for normal wear and tear was the alternator. Runs great, got about 20 MPG on the highway before the bigger tires, but the 3.4 is a much better engine. I wanted the fold down tailgate of the 2nd gen and at the time 3rd gens used were very expensive so I saved some money and put mods into it to make it more off road friendly. If you are looking strongly at mileage I suggest you buy an older truck with good mechanicals (cosmetics optional) and get a cheap fuel efficient car for commuting. You'll never get amazing fuel economy out of a heavy 4WD truck and most off road mods take even more economy out of it. That said, I drove my truck from El Paso to Seattle and back and was very happy other than the fact that I had no acceleration in the mountains.

I forgot to mention this. I drove both the V6 auto and 5 speed and the 5 speed trucks far and away drove better. The 3.0 with an auto is a dog!!!