Ok, so I bought a 2014 Mustang in September, has 34k miles. (Manual transmission)
Started noticing the rpms dropping during idle a couple weeks ago then Thursday, while shifting between 2nd and 3rd gears, the rpms jumped up to 7000! I shut it down and restarted, went straight back to 7000rpm.
I had it towed to the Ford dealer I bought it from (bought the best warranty I could) They couldn't get it to duplicate the problem but said the throttle body was dirty so they cleaned it.
Drove about 400 miles over the weekend (mostly interstate going about 80mph) and noticed last night that the idle rpms were dropping again but it's not done it yet this morning.
It hasn't thrown a single code during any of this either.
Thanks for reading and for any insight you may have.

 

So the first comes in mind is a software issue. The RPM acting up like that could be tune related. Any chance the previous owner loaded aftermarket tunes.

Not very knowledgeable in regards but what I understand is they change parameters. Maybe it was not done properly. How about try and have dealership check, reset back to default under extended warranty?

 

Yeah, it had a tuner control in the glove box when I bought it and the company said that it had had 2 tunes put on it. I don't know which tune it is currently set to or even whatever of them do. Starting to wish I had just bought a new one instead.

 

What kind of tuner control is it? If it is a SCT, you can 'return to stock' and see if that works. Unless you have a lot of modifications and you can't run the factory tune