Hi forum, haven't been around lately, the issues with our Bonneville back in January apparently worked themselves out! And, we just bought an '11 Lacrosse, a very clean ride, 4 cyl, with only 116K! When I test drove it, it was fine, until I got on the highway. Then, it seemed like I had my foot on the brake, couldn't get over 50mph, and it wouldn't upshift, sitting around 3500rpm. And the front end and steering wheel started to shake. I got off at the next exit, and on the way back, it seemed ok. I mentioned what happened, they said it was getting new front rotors & pads the next day. I test drove it again, and everything was fine, so we bought it, last Thursday. Saturday afternoon, I was heading home, and went on the highway, and it was doing it again, minus the shaking. I pulled over, backed into a parking space, and put it in park, hit the parking brake button on & off a couple times, just in case. I checked to see if any of the wheels were hotter than the others, but they seemed about the same. I went back on the road, and everything was fine again! I was talking to my coworker who does all his own wrenching, and he said the ABS has a memory that might need to be cleared, or sometimes the flex hose to the caliper has a separation inside, that can create a flap, that lets fluid go out, but restricts it coming back
The other thing is, the check engine light came on that first night, had it read the next day, code POO14, "bank 1 exhaust camshaft position timing was advanced beyond limits for a predetermined period of time". The day after, the light went off, and hasn't come back on. Wondering if that'* common, and should I worry about it? But the brake issue is my main concern.

A thought arose, while going to pick up my youngest from his summer program. Not being used to a different car, could my size 14 clodhoppers have caught the edge of the brake pedal, while stepping on the gas? I'd had that thought before, but dismissed it. It'* possible though, as I have neuropathy in my feet & calves, some feeling left, but not 100%. My wife'* been driving mostly, I'll need to be extra conscious of my foot when getting on the highway. So, maybe it'* a non-problem, but consider it just in case it'* not my foot!

My feet are almost as big, and I have some trouble with the newer cars' tight pedal placement.

If you did have the brakes on at all while also using the accelerator, it may have limited itself to preserve itself. Dragging the brakes like that will make warped rotors show their stuff as well, in the form of shaking the front end and steering wheel.

I'd say keep an eye on it (and your feet) and report back in a week or so.

UPDATE: It did it again while my wife was driving, and I was present. She made a left per our route, and it was ok again. I mentioned it to the Mr. Tire guy, and he said try using the parking brake occasionally. Since it'* a push button, not using it can cause it to get out of adjustment, and the computer could possibly try to correct it while driving! So, I'll use it from time to time, and see if it happens again. The first time it happened was when I first test drove it, and it was shaking pretty badly after a minute or two!

Hmmmm . . . I've never heard of that, but maybe that'* a thing. It would go together with the shaking if the parking brake was applying to a rotor that is warped.

I'm interested to see where this goes!

UPDATE: it started doing it again, I pulled over, put it in park, turned the parking brake on & off a couple times. Pulled back on the road, still dragging. Intuition told my left foot to slip under the brake pedal, success! The pedal isn't retracting all the way! I checked Pull A Part'* inventory, and they recently set a '12 Lacrosse in the yard, so I got up early, and went down to Charlotte. I took a lot of the lower dash apart, to get a decent look at it. Of course, it doesn't have a spring on it, it does have electronic stuff on it. I spent some time attempting to get the assembly out. It seems like it'* part of a larger plastic piece, that'* bolted to the firewall, with 15mm bolts & some nuts, which had really thin heads, and probably loctite, they didn't want to loosen, and it was already too hot out to fight w/them! There were metal plates around it with 13mm bolts, I got most of them off easily, but there were two on top, and not enough room to get a socket on. I did learn about how the interior trim pieces are attached, especially on the passenger side, my wife bought a dash cam, and I want to run the wires behind everything. It came with little sticky clips, that stuck for a couple days tops!

I wonder if you can cleverly attach a bungee cord to it to test your theory for a while . . . ?