Happened to me as well. It was bad fuel. Dealership must have used watered down 87 octane. Car did not even idle without choking. Drained fuel, techron additive and idle was fine but it would not rev over 4k on full throttle. Changed spark plugs and back to normal.
Especially if it did it after fueling, like in your case, has to be fuel or fouled plug.
After new top tier fuel, reset computer to see if it did go to limp.
Had this happen to me today in my '20 GT... Was driving around Chicago, just cruising through the neighborhoods, stop and go traffic, but not bad. Noticed that the car bogged down in 1st when I accelerated - 4000 RPM and nothing more. Pulled over, shut the car off and then back on, same issue. Pulled over again and let the car idle as I called the dealership. About 5 minutes on hold and tried again - back to normal. No codes. Guess i'll just wait to see if it happens again. Nice to still be on warranty...
Anyone have it happen again after commenting above?
Well, not eactly same, but similar. 17 400 manual, driving steady, power loss, engine goes to idle and no throttle response. Made to side of road, shut off, waited 30 min for software program resets, and started. Ran fine, went home. Treated throttle body connector with DeOxit 5 solution, no problems since; also no MIL or other lights. Took to dealer for check. Service manager said "throttle body connector" as I was describing, and treating as I did was appropriate; stated dealership uses Stabilant 22 in this instance. OBD check showed absence of any codes. No problems since, in approx. 400 miles.
So I have had this happen a few times randomly and there never seems to be anything consistent, or so I thought.
It happened twice recently and in both cases there was something consistent and thinking back, I think this has been the case for the other times as well.
As insane as this sounds, driving with the fan on maximum (heat or AC, does not matter) seems to be connected.
Last night it happened twice, both times the fan was on maximum. I tuned the fan down, turned the car off and then back on and the 4000K limit was gone.
Again today I was driving with the fan on all the way and got limited to 4000. I turned the fan down and restarted and the problem was gone.
I am going to retest this again this week to see if I can replicate this but I would ask anyone reading this to try the same thing. Simply turn the fan all the way up and drive for a few miles and then floor it.
can happen if the oil consistency isn't good or if the dealer put in oil the car didn't like. My 400 did the same when I first bought it, would periodically go into limp mode for no reason. if I stopped the car, took out the key, opened the door and then started it back up again it would go out of limp mode.
Once I changed the oil, the issue went away