I bought a 2001 v6 mustang from a dealer about 2 months ago and in the last couple weeks I noticed while sitting still or coasting the rpms will drop to about 500 or 600 and it starts to shudder but it usually bounces back up and down between there and 1000 but about 2 days ago i was at a stoplight and it was out of gear holding at about 2000 rpms and I had to rev it several times for it to drop. One other thing I have noticed is that unlike all other manuals I've driven the rpms do not drop right when I put in the clutch, it takes several seconds and then it goes down slowly. This part could be normal to these cars but I need some input. My dealership has been pretty good about fixing a couple other issues but not unless I told them exactly what it was. They so no problem until I could diagnose it myself so I need ideas. I'm thinking throttle position sensor? Thanks!

 

Tell them the "Idle Air Control Solenoid" is acting up.

 

Clean IAC and check for vaccum leaks. Don't need dealership for that. 2012! LOL! NVM! Are there any posts this year!?!?!?

 

Yes. I too agree with slow_2V. Hi Rachaellee! Have you tried looking for a vacuum leak?

 

Thanks for the reply.
I cleaned the IAC valve yesterday but same result after cleaning and today. (I will try with my old IAC valve, which I kept). I also disconnected the battery for an hour.
It happened only after I floored it in 2 and overdrive off. Weird as it sounds. (Murphy's law or the twilight zone?)…. I am always very careful.
I will have to look up how to check for vacuum leaks.

 

Sometimes the TB - throttle body gets dirty, spray some carb cleaner and wipe the greasy/gummy stuff with a lint free cloth - where the circular metal flap is.

 

There is no check engine light, I am thinking I have damaged something. I did swap the idle air control valve. That did not solve the lope.