Well got the dealer I bought the car from to pay $400 towards this problem.
So I said fudge it and replaced both the cat unit and rear sensor with OEM parts new gaskets and so on. :'( The after market cat unit that was on there looked as old as the rest of the exhuast. The flange bolts where half way rotted off. So I just cut them with a sawz-all. There is no way that thing was just changed 1 1/2 years ago. The sensors came out without a hitch. Also Starky Ford had put 5W-20 oil in it about 500 miles ago. ??? (where the car was traded in not where I purchased it) and a motorcraft oil filter. Now that is no way to treat a Subaru. >
So I put on a OEM filter and some 5W-30 Amsoil in it and boy don't that thing run smooth now. The motor runs and sound just like my 07 Impreza. minus the Prodrive and the improved power of the MY07. You guys know what I mean. It sounds and runs like it has 20k for miles not 88k. So in my opinion sometimes going with cheaper will cost more in the long run. It is a real easy job for the most part.
Thanks to all with the advice and of course to the all mighty parts goo-ru Joel. 8)