My Tribute died while at the Mazda dealer getting a new brake boost and fuel filter

Visit the garage and listen for the fuel pump after turning the key ... if you hear it come on then go off within 5 seconds of less then the Tom above has the problem spotted. The Hissing noise could have been the garage mechanic

I would have taken it somewhere else for another opinion. IMHO if the car were making a hissing noise that was the brake booster that would have meant you had a vacuum leak and your car would have run like crap at lower speeds and enough of a vacuum leak would have set off the EGR warning

Go to the mechanic and push the Fuel Pump Relay Switch Reset. It is on the passenger side front floor panel. Open the little flap on the side where the passengers right foot would rest in the front seat. Put your finger in the little tube and push it several times. It should start- mechanics trick to crank up costs.