Sounds like a clogged cat to me. Have them check and see what codes are stored.

 

No you can't. If the t-case is munched up inside, putting it in 4wd would only make it worse. Driving your truck on dry pavement in four wheel drive is also a very good way to break parts.

If it is the trans that is the issue, putting your truck in 4wd would make zero difference.

I don't think you picked a very good shop......

 

The codes need to be checked, simple as that. The transfer case is not going to set off a CEL. If it shifts fine and goes in and out of 4wd fine, I'd say neither of the two are the problem. Plus the only time there was any kind of noise (according to the OP) is when the truck was sitting still and his wife revved the engine. Unless I read the OP's replies wrong, there was no noise otherwise, just a loss of power/speed.

 

Found out today the T-case is fine and the torque converter is fine. I'll find out exactly what the problem is today.

 

Ok they found the problem that caused it all and its the Cat.. so they replaced that and currently doing a tune up and I can pick it up tomorrow!

 

Now you need to do a search here on DF for plenum. That's why the cat is clogged.

 

nice call john