Hi I'm new here, I'm asking regarding my friend 2003 escape, we did to change all gasket due to oil leak, valve cover gasket, timing cover gasket and seal, and oil pan gasket! when I start the car, some misfiring found, I drive the car then after that smell fuel and smoke when I open the hood! And the misfire that I found from cylinder 4 and 6, I check the car and i fix the problem runs good! So I test drive the car, after I driving for a few km. The car slowly no power And pitch sound, some like wisstle! I think maybe the catalytic converter is clogged! So I decide to take it off the front nut of the catalytic, start the car and really loud sound, but I'll try to test drive, the car runs fine, then put back the front nut bolt and test drive again, the problem came back, and no power! I wondering whose catalytic converter clogged the front or the back or the middle! Please give me some idea and help what catalytic converter clogged.. my friend doesn't have much money to buy all catalytic converter! Thank you for your help..

 

An exhaust shop can do a pressure test to see which one is clogged, but it is probably the front one since there were two misfiring cylinders on that bank.

 

I remove the front muffler and the middle, and I found the middle catalytic converter is clogged. So I suggest to my friend to changed it! Its possible the problem come back after we changed the middle back catalytic converter?