I live at 7800 feet and go to 10K up to work. Some of it is steep and I go to second (rough road and I'm in third, 4wd for bite, even on dry, going 20mph). One spot I go to first (steep) but at no time am I above three grand. No need. Sounds like we have a close set up. 16" BFG mudders. No CAT on my '92 (156K miles) and dual exhaust, K&N filter so it's 'abreathin' I'll give you that. I just listen to her purr and enjoy the view. Haven't found a need to hurry and she has plenty of pull and is by no means gutless. A little slowing at times but nobody's honked at me yet. <img src="/forums/images/graemlins/lol.gif" alt="" /> Guts does not egual speed if speed is what you're after.

Aside from that... I can feel she still has plenty of power and will not crap out on me. I don't expect to rush up there at 45mph. Is all this stuff happening in 2w, 4wh or 4wl? What's the path like and how fast do you want to go? Maybe it's just the nature of the beast. Mule, horse, thoroughbred. Mines a lot of all and I expect no more from each aspect. I don't think you have a mechanical problem.
The plugged CAT response is a definite maybe. I don't think it's an altitude problem. Where did the 4R come from?

Long, steep grades on the interstate I move over and usually end up in third and keep it around 3Krpm and let the big guys fly by...don't care. I crest it and I'm on my way. Doesn't feel gutless...just part of deal of having a good horse. It can do it all.

$0.02....-d.... <img src="/forums/images/graemlins/cheers.gif" alt="" />