odd idle

[snake109]

when i come to a stop the engine dips down to about 600 and i can feel the vibrations prety bad and if its night the lights will dim, but it doesnt seem to do this with the a/c on, or if the engine is cold. whats the deal? its a '93 5spd

 

[Mr. Rustypwnz]

We have an old 90 honda accord that will do the opposite when you have the air on at stoplights. It feels like it puts a huge strain on the engine and starts vibing. Im sure the mustang when you crank the ac the engine compensates for the power that the ac is putting on the engine, probably making it to idle better. Just twist the screw on the throttle body clockwise until it stops. If this dont help, my advice is to buy a 5.0.

Josh