I put 85 gas and car recommending 87

How much 85? if under 1/2 tank it should be okay. If you are really worried hit a parts store and buy some octane booster. It sounds more like you got the lowest tier stuff from the description.

Hello,

Depending on your location or elevation this may or may not be ok for the time being. For example, if you are in a state with high elevation like Utah, it will likely be okay for just a tankful of 85, as long as you put 87 on the next fill up. Sometimes people will put higher octane in the tank when it is half empty just to help with the overall octane that is inside the tank.

And in cold morning air is much denser witch trigger the knock that happens when putting lower than recommended octane in the vehicle.

Did you fill up all the way?

So, there are few variables that can determine if this is okay, or you will need to drain the fuel tank and put the correct fuel as this can impact the drivability.

Let me know of any questions.
Thank you.

Thank you both for the response. To elaborate - I am in Denver, so definitely higher altitude.

I did use the 85 rating, which here is regular, and I for idiotic reasons did not notice, I just saw regular and pressed it as I moved here from the Midwest couple of days ago where 87 is regular. It is at half tank currently and I will put higher octane in tomorrow morning if I can get it to drive without the rumbling/vibrations.
I did fill up the tank to full, now half full. Was fine driving for the last couple of days, just tonight when I tried going out, I did not leave the parking lot.

Still unsure what is causing this rumbling in the engine, it is only when I put it into drive, none when I have it in neutral or park, or very minimal. Was not expecting this out of a car that has under 3,000 miles on it bought brand new.

Thank you again.

Open the hood and watch the engine and have someone hold the brake and put it into drive and see if you hear anything strange outside the truck. That truck has a fake engine soundtrack that goes with the new design, what you hear, and feel may not be the actual engine. To make it sound more like an old school Bronco Ford added a soundtrack that plays over the stereo system in the truck to make it sound like a V8. Plus, the actual engine in that truck isn't known for being a quiet engine once it starts to break in.

Since you are at high altitude the octane rating will have minimal affect.
Let me know how it goes after you fill up with higher octane.
But as Steve mentioned, this noise might not be related to the fuel at all.
But either way give us an update. Thank you.

Update:

Put 91 in there to top off the tank, seems sluggish but might just be the car, as I've always felt it is underperforming compared to my VW. Did not experience the shaking, rumbling of the car in the morning when I went to get gas.

Took it to the Ford dealer to get it inspected. Was told that I would need to leave it there for a week or so to get inspected and that it could be a number of things (thanks, could've also told you that it could be a number of things, lol) left with "bring it back if it happens again".

Not a car expert obviously, however that sound and the shaking seemed very bad to me for a new car that has barely 3,000 miles on it. Honestly, even an old car. Had my previous car VW for 65,000 miles and cars before that, never have I experienced this. Wish I could articulate better with this issue or have taken a video. Appreciate the help fellas.

To add on to the fake engine noise. It was not just the engine noise, the whole car was shaking, the hood of the car was shaking and making very alarming sounds.

So, it is driving normal at the moment?

You know those 3-cylinder Broncos are not known for high power. But it should not shake or rumble.

It is possible that the lower octane triggered that shaking under the specific condition. Sometimes the engine management system will learn or adjust the fuel delivery to compensate for the octane. As you have higher octane fuel it is likely just went back to the normal setting.

One thing is true that unless the issue can be duplicated, they won't be able to diagnose of what might be causing it.
Many times, in random or intermittent issues only way to know what the cause is it to be able to duplicate the symptom.

You should drive this vehicle normal as always and see if the shaking comes back. At that time, they will be able to attach the diagnostics to see what the issue could be.

To add a bit to Sean's answer. A 3-cylinder engine is going to be rough running even at the best of times. It's possible that the shaking was caused by the system adjusting for the octane, or it could also be that what you bought was just bad fuel. Usually, the economy grades are the stuff that almost passes as gasoline. They take a low-grade base stock and add ethanol to it to raise the octane up, then add in a witches brew to cover the rest of the items the fuel needs to have. It wouldn't take a lot of bad fuel to make a 3-cylinder engine buck, if even one cylinder has any sort of issue it is going to shake really bad.
As for being underpowered, they are very underpowered. Everyone seems enamored with the HP ratings but never look at the torque and RPM range of those small engines. Having an engine like yours that produces 181 hp and 190 ft lb torque at its best and needing to be running at 3,000 RPMs for that is going to feel a lot like a turtle running on oiled glass.
The reason is simple. HP = speed but it's torque that gets you moving. In the Bronco you are pulling 3,500 pounds around with that, and there just isn't much pulling force until you really step down and get the rpms up and get some boost.