I commute 80 miles each way to work and my car is running like crap. Once it gets warm it is idling very erratically which makes me think that the stumbling-bucking happening when I accelerate, mostly on inclines, isn't the clutch.
I replaced the fuel pump (had a used one) and filter. It idles ok sometimes when hot but won't last long. If I keep it at high rpm up hills it's ok. Turns I would make in 3rd need to do in 2nd or get the stumbling.
Don't have a tack so can't use that.

Any insights? I would like to know for certain that it isn't the clutch, think I should take it to the dealer for that evaluation or will any "good" mechanic do?
Thanks