03 Ranger brake problem

Best way to find out if it is brake booster is to take the big rubber line off the booster and plug it so it can't leak then start the truck if the hiss is gones away yes it is the booster. There not really that hard to do. 2 -15mm nuts takes master cyclinder loose. Don't break lines loose at master cyclinder just real easy move it out of the way.A leaky booster could cause several things to to happen on the truck loss of fuel milage, poor idle, poor exceleration, stumbling etc. Ok back to the booster go inside the truck look under dash you'll see the rod coming through the firewall going to the pedle there is a steel clip through the pin that holds the rod inplace, watch how this comes apart cause you will have to put it all back just right or your brakelights won't work cause your brakelight switch is also mounted there. Then take a 13mm socket and an extension take the four nuts off the booster just follow the rod towards the firewall and you will see the four nuts remove them and pull the booster out. And just go reverse to go back peice of cake.(NOS)