Ok.. so I have been using the mustang more then ever now that we have been having such nice weather.. well anyway.. i notice sometimes after using the car for a while that when i go to put her in park she starts reving up to like 1500 rpms.. sometimes if i hit the gas she will drop back down to normal but other times it goes right back to 1500rpms.. im thinking that maybe the throttle cable is getting stuck but not sure.. since when it goes into drive it will drop right back down to normal.. just wondering what it might be.. thanks

 

Vacuum leak? Do the rpms ever hang anywhere else? Maybe the IAC?

 

What do you mean by "hang".. I do notice that sometimes when i tap the gas pedal, and i mean tap, that it will rev stay a second and then drop slowly.. almost like it holds the rev even though i took my foot off the pedal... how would i check for a vacuum leak?

 

check your IAC... that is usually the culprit of hanging RPMS/wont start/bad idel/etc.

 

If it were the throttle cable or plate(s) sticking you should be able to manually pull it back. The mere fact that you says it happens sometimes, especially with changing weather does point more commonly to the Idle Air Control valve. They get dirty and need to periodically cleaned. Usually, with a little time, a rag and a can of TB cleaner (electrical parts cleaner works too), the issue will go away. If so, the internal solenoid could be bad, and thus, requires a replacement.