2016 F-150 V8 Sport
57k miles
New transmission at 53k (I know, ridiculous.....)

I came to a light yesterday and was sitting there and the truck slightly shook and the tachometer went lower than idle, than above idle. Almost felt like it was going to stall out.
Came to a 2nd light, and same thing.

Then got home and stopped in the driveway, while still in D, and was fine. Put it in P for a minute and sat there. Was fine.

Anyone experienced anything similar? Thoughts? Thanks.

 

Well, crystal balling it and based on some knowledge, I would first blame the Throttle body.
It contains all the Idle function responses.
The hint in your post that in Park the Idle is stable suggests there is little to no RPM correction needed in Park or Neutral so Idle 'hunting' is not happening.
In gear, the Trans is a load on the engine through the torque converter and will affect Idle speed that would be corrected in a fault free system.
The Throttle body may need to be removed and cleaned.
There is a yu tube vid on this for the looking.
Good luck.

 

Thanks. I'll research that.

 

Same engine. Battery on its way out. New battery and it idles fine now. It does do some weird stuff at times coming to a stop at a light. I'm at about 80k and I should probably do the plugs as well..

 

When the battery is disconnected for any reason, then reconnected, the PCM is rebooted and goes into a full set of self-diagnostics that clears all tables of learned driving info.
You will see a difference in drivability that is a normal result until the PCM learns all the variables that it deals with during multiple drive cycles.
Battery replacement by >>it'self<< did not fix any NON POWER issue/fault that was present before the battery was disconnected even though it looks circumstantially, like it did.

 

Well it's been months and my truck is idling just fine. Had a few rough starts and I could tell the battery was getting tired. Then it left me stranded. But it was stuttering bad at idle the last couple days before I changed it.

 

So.... My battery is about 1 year old. But, last Wednesday someone left one of the overhead lights on inside the truck.... all night. Truck started just fine the next day, and then was fine but then had this revving / idle issue a couple days later. Seems weird that it would be a couple days later, but could be related.....

 

Probably not. But they do weird things with low volts. Spark plugs would be my next guess.

 

Fair point. Never changed the plugs..... Seems like a little early for that, but ya never know. I never thought I'd have my transmission / torque converter crap out at 52k miles either...

 

Yah that's rather frightening, they just aren't made very well imo lol. Good luck