While driving at a constant speed ie 45mph or 65mph the vehicle hesitates

I also have a 2012 Acadia with the SAME problem. I took it to the dealership numerous times while under warranty and they were not able to duplicate my complaint. My car started going haywire one day only to find out that the junction box was full of water! How does this happen? No one had an answer for that BUT....each time I would start the car the engine light would come on and give a diffrent code each time. Long story short while having the junction box (main fuse box replaced) at a dealer out of town while on vacation, I mentioned the lunging, skipping, lack of power issue and they said it was a bad purge valve sensor and changed it while they changed the junction box. If you still have this car GET RID OF IT! This happened to me in June of 2015 amd cost me $1200.....today I took my car to the dealership for a front end vibration and bumping sound on the right side (which has been happening for over a year and progressively getting worse, yet, while under warranty they could never duplicate the problem) now that I'm 17,000 miles out of warranty....they tell me the front struts, ball joints and bearings are bad $980 plus tax and the roaring and vibration is due to a bad gear housing in the stearing??? ANOTHER $900 plus tax! I called General Motors Corporate office to file a complaint on this dealership and this POS car only to be told that he these cars are usually off the road for good at 130,000 miles!!! STRAIGHT UP JUNK! I have already replaced a water pump, the junction box (2 times because the 1st one was bad) spark plugs and wires (because they attributed the skipping to a miss fire on 2 plugs and the car had 70k miles on it) new front brakes and roters (because that's what they said was causing the same vibration that is now bad struts, ball joints and bearings ) I WILL NEVER EVER OWN ANOTHER GMC PRODUCT EVER!

POSS UNDER WARRANTY AT DEALER

I have a 2010 Acadia with CONSTANT transmission issues to include this one. It also hates the cold weather, and will occasionally decide to flash "Engine Power Reduced" and suddenly drop down to 20mph and go no faster even when I press the gas pedal. Very dangerous as I live on a very busy route where people hustle along at 60mph or better. Paid $200 recently to have it towed to my mechanic who, by then, could NOT find ONE single problem with the damn thing. Cost me $110 just to hear that. Not to mention this vehicle burns oil like you read about... Even my first car, a 1988 Ford Taurus with 150K on it, didn't burn oil. Stands to reason a 2010 with 40k on it should NOT. Never again with a GM product, never.

I had the exact same problem with my 2009 Acadia. The problem was with the cylinder ignition coils. I have had 5 of 6 replaced and am beginning to experience this problem again. I suspect the 6th of original coil is now going bad.

I had the exactly same problem with my 2014 Acadia SLE-1 2WD. It feels like a dirty or clogged fuel filter or a slip in the tranny, no “check engine lights”, no codes but only “Service stabilitrack”(?) light on.I was thinking it is something wrong with the transmission? Injectors? or maybe it is that the fuel injection throttle body assembly is dirty ? Uhmmm. I cleaned the injection throttle body assembly and nothing change at all. I keep driven the Acadia till I realize the back brake lights were stuck in on, like if I was pressing the brake pedal. I read about it and I learned that the Brake Pedal Position Sensor does a lot of more than just the back brake lights but send information to the car computer to control things like the amount of fuel the cars needs in some conditions. I got the part from the dealership for $13.98 but you could get it even cheaper in Amazon for $10.64 Original Equipment. The brake pedal sensor is right there over the brake pedal, you need to take the plastic cover that is hold by 3 clips, and the part is hold by just one bolt, the whole thing only takes a few minutes to replace. Right after that I went to test the Acadia, no problems at all, it feels like a brand new SUV, I drove the car around 100 miles in the freeway to make sure and the car works perfectly. I can’t believe that just a $10 dollars part/sensor was the problem but it was. Now I have been driving the car for a while, like 4 months and no more problems, none.