Random Misfire Detected

[Goofy173]

Something got plugged in the exhaust and then it blew out, blowing out material because of the high pressure that was built up under your hard acceleration. I've seen exactly this in my Ford 460 and at 80 k miles.
Everything was fine and just as I started climbing a grade and accelerating, boom, lost so much power it would only idle, check engine light on, obd1 though. so I did not bother with codes. Turned it off. Inspected, restarted, hit the accelerator and I heard a muffled backfire and crap flew out the exhaust and then all was well. In my case it was the cat. Since it had already blown out the plug and more, I just left it, as otherwise the exhaust system was solid.

 

[tacoduck]

Was it perhaps raining? I had the issue on my 2017 expo in rainy damp conditions.

 

[JustHarsh]

No idea when the stuffing came out the turkey. I never heard any suspicious noise leading up to the hard accelerated and the check engine light. Once I slowed down to coasting for 10-15 seconds and the check engine light went off I was able to accelerate again and made it home (1/4 mile).

I've been keeping track of mileage, as I've read that could be a sign of bad cats, but I've been getting pretty good MPG. Took a little road trip last month (500 miles) and got 19.2 MPG. In town I'm getting 17.9 right now.

So far so good.

 

[jeff kushner]

The 2017 Expy is a very nice truck............you didn't go wrong OP. Your coils and plugs fail first under load and at 85K, it's time for both...you got the early warning flags! LOL

I would have done plugs and coils as Loki said, yeah the expensive ones and as Train says, leave the muffler alone, pull out what is loose.

fwiw and the OP's peace of mind...........mine has 138K on it, bought new. Nothing has ever broken.........no codes, no runs, no errors.......oh, I did replace the center console hinge pin spring, it broke...35 bucks...does it even count? LOL
My mileage since new is 18.4. It was 18.5 but dropped over the winter, prob due to oxygenated gas. Each tank returns 19.2 or so MPG