I drive a 2005 mustang GT 5 speed and it has started acting really strange. I mean i took it on a little road trip about 3 hours long and when i started back home i noticed my check engine light was on. So used a hand held and noticed that the problem was reading as low RPM's. The car just sitting at a red light will go from 650 to around 1100 rpms.

HELP i dont know what it really is i think maybe vaccum lines but i dont know also will this hurt my car??? thanks

 

It will not hurt the engine, but it's still a PITA.
Make sure all connections are tight on the air intake, and change the air filter if the mileage is high on the old one.
If no luck, then clean the MAF sensor and throttle body.
If still NG, then either the TPS(throttle position sensor) or the TB may be bad.

 

What is the actual code and please describe the exact symptoms.

 

without knowing the engine code, i'm voting for dirty maf.....then bad TPS sensor

 

My car is doing the same thing..except mine will actually stall out. I had the Ford cleaning of everything in the air path about 2 months ago as well as fuel filter change.

mine does this intermittently though so it more difficult to diagnose...

 

if it's actually stalling, perhaps replace the Tps. i bought one for $55 at ABC auto. fixed my problem of not being able to hold an idle and stalling out