I have an '09 LT2 V6 and the only time it shifts "correctly" is when you are on a flat road and accelerating slowly.
If you get on it too hard from a standing start there can sometimes be a long hesitation, if you are on the highway and want to pass if you hit the accelerator to hard it downshifts to much causing the car to rev way too high and if you push down on the accelerator too softly it will not down shift and attempt to accelerate t at too low of an RPM.
The other problem is the trans does not downshift when decelerating forcing you to constantly use the brakes when going downhill.
I also have a problem with torque steer especially on roads that have indentations form heavy truck traffic. If I accelerate hard the car pulls all over the place. Don't get me wrong. This car is head and shoulders above my other Malibus but the shift logic in the trans stinks. My other car is an '09 Infiniti G37XS with a 7 speed trans and it shifts perfectly every time no matter what I am doing and will hold it's speed going down hill without having to touch the brakes. ...
Hesitation from standing start. Some vehicles won't allow to the pedal starts because it is considered abusive and could make wheels spin. I don't know if this is one of them. As to revving too high, is it going red line? Otherwise it might be considered normal for vehicle when you want maximum acceleration. You might try varying the accelerator depress rate and backing off a little when it shifts to where you want it, as others have found that works.
You have not indicated where you live so we might grasp your hill situation. I hope they are not so severe that you have to slow way down so as to not outdrive your visibility. I have not yet figured out when engine braking is supposed to exist or if foot totally off accelerator will engage some of it or possibly light braking will add it. It would be nice to know.
I needed engine braking coming down mountain grade. It was a bit annoying because I was used to pulling the shifter from OD to D and if more was needed, just pull it another notch. To force enough engine brake, I had to reach over and pull it into M, then find the paddle shifter and work it. I had to use a combination of lower gear and braking. With a smaller engine you will not get as much engine brake, say compared to a NorthStar V8.
Torque steer. Overloaded truck wear grooves can be annoying to say the least. I have not yet experienced a major issue in that avenue. Torque steer has been little on my vehicle.
Are you running tires at correct inflation?
What size and type of tires do you have?
Has the alignment been checked and what are the figures?
I had a vehicle that handled such beautifully. It likely had more range of motion in the horizontal plane of suspension than many vehicles because of different design. Also the tires I had on it had soft sidewalls and usually looked low on air even when set correctly. The tires were decisively among the very best for the vehicle according to everyone who tried them. Rating was for handling, noise, response, and traction. When coming upon such grooves, you could literally feel the footprint of one side of the vehicle move while the other side tried to remain stationary. If it was a short problem, the vehicle would come right back to where it was. If it was long enough, then the other side of the vehicle would adjust for best tracking.
With the BU it might be difficult to acheive this because I think I read somewhere that the wheelbase for the front and rear are different. That would make either the front or rear react sooner.
You might improve the torque steer issue by adjusting the alignment. I don't know what the correct specs are for this car, but I suspect they don't have the correct figures at the dealer. They used chart for older BU with 4 speed.
Per that spec, the RS front gets more camber than the LS. I was told that was to help with pulling to the right on roads with crown. Such a setting might have an advantage when driving the oval as well. My driving, I'm likely to encounter crowns going both directions or just flat road. And the caster was set higher for the right than the left. If I were driving country roads where the most defects would likely occur toward the edge of the road, I think it would be better to have the higher caster toward the center of the road. Caster is intended to keep the wheel pulling the car straight and the more of it would be fine on perfect roads. However, when running grooves such as you are, minimum caster would probably help control.
If alignment is correct, the contact patch of the tire must also be equal from LF to RT. Rather hard to do with severe road grooves. It would take a tire that is able to flex enough in the sidewall and the tread to maintain full contact at all times.
Hopefully you can work it out. At least you do not have the feeling of play at the steering wheel.