Moved you to the Technical Chat area so more people could see your problem.
Did you change the PVC valve when you replaced the hose? I've had my cat break in clog before it made the car very slugish just trying to keep up with normal traffic. Wait till it gets dark and go for a little drive. Then pop the hood and look at the cat. If it's bad it may be glowing red hot in spots. Mine got so hot it turned blue. How many miles are on your car? T-belt should be done around 100-120k mi on the normal zetec