It doesn't feel like a slipping clutch....There's only about 58k miles on it.My first guess would be a slipping clutch. How many miles on the clutch?
You can test for slippage by accelerating (and/or popping the clutch) at a very low speed ( 10-15 mph) while in a higher gear (4th or 5th). If the engine revs freely the clutch is slipping. If the clutch is not slipping the engine should bog or at least struggle slowing against the higher gear.
I'll try the way you suggested also.
I really smells like clutch to me...And would brakes smoke like that? I'm not talking about driving for a long period...like the other day it did it after merging onto a road then immediately going into a turning lane (where I noticed the smoke) I only got into 3rd gear BTW...You should be able to tell the difference between a clutch and brake pad smell.
Just take a whiff close to each wheel.
(good thing there isn't asbestos in the pads!).
I also noticed that shifting into 3rd gear when getting into there's a lag between the gas and actually "going" (if that makes sense, or even has anything to do with this)