Did I break something?

Hi All - Sorry it's somewhat of a long post, but looking for some help.

Had a '22 OR 2WD for about a year, but the beginning of January 2025 I traded in for a 23 OR 4x4.
New truck is all stock, fell in love immediately. Never had complaints on the power of the old truck but the new truck felt a bit more responsive, I'm guessing because of the stock tires('22 truck had KO2s but the same size).

Anyways, after 2 weeks of owning my new 4x4, I tried to ascend a steep dirt/rocky hill near my apartment that I previously tried with my 2WD that couldn't make it. I was about half way up and was climbing with 4 hi and then I decided to try 4 lo. Put it in neutral, turned the knob to 4 lo, back into drive, let go of the brake and obviously started rolling back and out of sheer instinct I stepped on the gas somewhat hard. From my understanding this is a no no with 4 lo? Made it up the hill no problem afterwards, and came back down.

The problem:

First thing I noticed after coming down, my brakes made a squeal sound when applying the brakes. Just your typical sound that means the pads most likely need to be replaced. I'm guessing I cooked the brakes from going up and down the steep hill riding my brakes too much. (To this date, I know not to do this now and use engine braking/1st gear etc). Second thing I noticed was the brake pedal now makes a "squishy" sound every time I press it now.

The brake problem isn't the real issue here, just wanted to include that in case it has any correlation to my main concern which I'll explain next.

After coming down the hill and putting it back into 2WD to hit the road, I noticed my truck was sluggish. I usually have a light foot on the gas and would have no problem getting up to speed by doing that, but now it feels like I had to go pedal to the metal just to get to 50mph. It will speed up rather fast to 50mph but not without gunning it, if that makes sense.

Around 40-60mph I also hear a "Howling" sound coming from the back of the truck after this incident, I have found multiple youtube videos with people who have experienced this sound with their trucks and it ended up being a bad rear diff.

I'll summarize the rest of the time line from when this happened to now so this doesn't get to long.

-After few days of this happening, the problem didnt go away, so I unplugged the battery and it felt *better* but not like before, but only for a few drives then it went back to the same.

- End of January, I took it to Toyota, didn't mention the 4LO incident, I just said it happened out of no where, they didnt find any issue, even with the brakes. I forgot to mention the howling sound at 40-60 mph. They reset my 'transmission' to relearn my driving habits to see if that will help.

- 2 weeks go by, it's still the same, but sometimes it feels worse than other times but never felt the way when I first bought it. I began questioning my self, maybe it was in my head?

-3rd week after toyota visit, Truck all of the sudden felt back to normal. Acceleration and shifting was smooth, everything just felt normal. At this point I knew it wasn't in my head. This lasted 6 days then went back to the old way.

To this date, it has been back and forth of feeling OK, horrible, and even a few more times of it feeling back to the way when I first bought it.

To summarize the problem, when it's running "poorly":
- Have to push the pedal down hard, I even feel a bit of resistance in the pedal as if I was climbing up a steep mountain road. This will occur on a perfectly flat road.
- It seems as if the truck won't shift to the next gear if I don't have the pedal to the ground(I'll see the RPM get to 2.5-3k just to get to 30-40mph). I don't have a full understanding about transmissions/shifting so maybe I explained this part wrong or it doesn't make sense.

-Did I break something by pushing the gas too hard on 4 LO?
-If my rear differential is bad based on the howling sound I am hearing, could this be the cause of my intermittent sluggish power issues?
-Could the brakes be related to the power issues?

I'm going to take my truck again to Toyota to mention the howling noise, I was just curious if anyone has any thoughts on this. I want to love my truck again

 

I would try going through the procedure of 4high to 4low ..then back to 2wd … make sure to do it on a dirt road … maybe something didn’t engage back to normal after . The howling is kinda normal on these trucks …u can also try changing out the fluids and see if any metal particles come from it .

 

I've taken it on many trails ever since this has happened using 4 HI mostly but now that you mention it, it wasn't until I used 4 LO that my truck started running poorly again after that 6 day stint of it running normal.