Plugged cats?

[ummduh]

Ok, well I have an 87 stang, 110,000 miles on the original drive train consisting of the standard 302..

Ok, well I seem to have a performance problem, but the car has been running great untill recently so I haven't really investigated.

The other day, on the freeway on ramp, got on it, and it hesitated for a split second, just enough for the front end to drop back down. Everything was cool after that for about 11 miles.
All of a sudden, the engine just started laboring. Well sounded labored, more than usual. I've got a K&N open air filter, the intake was louder than it ever was.

Well, it bogged and bogged and just kept going slower untill I could get to a place to pull over. Felt like I cooked the trans actually. So I checked, and it only was about a quart low. (getting the trans fluid took about a half hour, so it sat there.) Filled her up and took off, worked great for about a quart mile, then bogged down again. This time I was hearing a hissing from behind the engine everytime you opened the throttle. So I checked to see if I was spitting tranny fluid from a rusted line or something, but nothing. Checked all the visible vacuum lines, all good.

Well, I nursed it untill I got it close to my house, and in a garages parking lot. By now, the engine was running very badly, surging and missing at idle. Wasn't responding very well to WOT-blips either. So I went home and got my code-scanner to see if It had set any codes. I only got thermactor failuer (bank 1 and 2).

Ok, well by the time I got back to it, it was running great. Back to what it was. Drove it home and a couple more miles of around the block driving, seeing if it would do it again. It hasn't. I haven't had the guts to take it back on the freeway, but I've had it at a sustained 55 for a mile or so and it hasn't done it.

The other thing I noticed now is that one of the cats is rattling. So..

Ok, I know this is long, but heres backround on the car.

It sat in a guy's garage for like 6 months as he was trying to get it to pass emissions. He did the exuast (supposedly including a cat, or maybe all of the cats..not sure) before he went on to messing with it.Then the TFI went bad, and would only run at WOT.. while they were messing with it. They weren't computer literate and just replaced stuff as they saw fit. All I had to change to get it to run was the TFI. So I'm thinking that lots and lots of raw gas ended up in the cats also.
The other thing is that this car is a DOG. (before this happened) I'm counting 12-15 second 0-60's. I got my *** whooped by both my 90 G20 conversion van(with a tbi 350), and a freind's 91 automatic escort! I thought these things were a bit better than that.

So, what are your opinoins? Anyone really know how to go about using a vacum gauge to check for exuast restrictions? I think it revolves around that it has to drop to 0psi at WOT, if it doesn't theres a restriction?
Keep in mind it's like 10 degrees out here in WI, and no access to a garage!

Thanks!
Matt