Sounds like the reason you need it replaced is because it is plugged. I know, my 96 civic ex did the same thing. They are pricey, but I was adding a cat-back exhaust anyway and I just got a high flow converter. Any converter will be expensive, they really aren't cheap, I got mine for 175 and that was off e-bay. But beware of e-bay they sell stuff that doesn't work, or will throw a Check Engine Light. Just do some research, the internet is great for that, and you will be ok. I don't think your mechanic did anything, but since the O2 sensor in the rear is not getting any input, the computer might be dumping fuel in and richining the mixture which would cause a drop in fuel mileage.
Monday, January 30th, 2006 AT 11:26 PM