I finally got my 4.7's in the t-case and headed up to the sierras last week. Did a couple trails, signal peak and gold lake to snake lake. Rig ran great until i was all the way down at snake lake, in the middle of ˟˟˟˟˟˟ nowhere, and it started crapping out during climbs. The engine would rev up a bit as i gassed it when climbing, but then lost power. It died a few times when i let the RPM's get lower than 2500 or so. I managed to get it up and out of the canyon ok. It runs fine on the road, and no noticeable loss of power when in 2H and street driving. Went to Prairie City today to test it and see if the same thing happened, and it did. Crapped out a few times on some of the medium tough obstacles. Just won't make power at low RPM's. I've read a bunch about causes of this, vacuum leak somewhere, EGR valve, VAF door spring tension, etc... Before i get into it i wanted to throw this question out to y'all and see what comes back. I'm sure hoping it's a simple fix, but who knows... Thanks very much!