Strong smell when idling

[Dan BB]

Wife took her 2004 Buick LeSabre to a mechanic (3rd time now), to have a new rack & pinion put in. They said they needed to drop the engine to do it, and since getting it back, every time we stop at a light or stop sign for any length of time a very strong smell of gas fills the cabin. Like I said, we've taken it back a few times and they say they still find nothing wrong. Although last time, they did admit to smelling the gas smell. Also, there has been some fluid leaking under the car that is the color of prestone coolant (florescent yellow), but its more near the middle and back of the car. Any thoughts?