90 town car lack of power

Hey guys, my friend has a 90 town car with the 5.0 in it. She stopped driving it last year because the car lost most of it's giddy up, can't climb hills. She said it also idles rough and it stumbles when you hit the gas.

I went to look at it, and immediately found 3 broken vacuum lines, one to the fuel pressure regulator. I repaired those lines, and that made the car run smoother at idle and reduced the stumble when you blip the throttle. I attempted to drive the car, but it would not climb the hill in her driveway. RPMs come up, car moves fine, but then it just won't make it, almost like a slipping Trans. Engine doesn't bog down, and the car doesn't roll backwards down the hill. I hooked up a SnapOn solus pro to it and ran the KOEO and KOER tests. The first test came back with several issues that didn't seem like they would affect this issue. The second test however failed due to the pcm couldn't command engine rpm for the low rpm or high rpm tests. The car doesn't deem to want to rev very high either.

What steps do I take from here? I don't know very much about these cars. Trans fluid level is good, fluid is not burnt smelling. Could not find any more broken vacuum lines. I'm scratching my head here guys.

A professional mechanic told me it's probably clogged cats. Thoughts on that?

A professional mechanic told me it's probably clogged cats. Thoughts on that?
Some cats have a removal "bung" plug in front of the cat for testing. You can remove this and see if it improves. Tend to agree, cat..

You should check every Plug Wire for corrosion. If one or more is rusted and making a poor connection, therein lies the problem. A clogged CAT is a real long-shot here as they seldom get clogged.