Originally Posted by Coryshade1995
It's in the transmission and for some reason mines bad because it doesn't hold transmission fluid for more then a day.and I'll look under the car and there's no puddle of fluid
He's right it is a vacuum modulator.
If they go bad sometimes the diaphragm ruptures and then your engine vacuum will draw fluid out of the transmission into the engine intake where it will eventually be conveyed into the cylinders and burned.
You can pull the vacuum hose off of the modulator to see if it has transmission fluid in it.
If I remember correctly it is pretty easy to change, there is one bolt holding a clamp that holds the modulator in place. If there is a steel rod in the modulator when you remove it, it may need to be removed and placed in the new one.
Read the instructions or buy a manual explaining how it should be done.