Do you have the power?

What up fellow mother truckers? I have a 1998 Dodge Ram with the 5.2ltr V8. I have noticed in the last year or so that my Horse power has been taking a crap. I have 97k miles but logically speaking that isn't that bad. Especially since it has been babied since day one. I put a K&N filter in and I switched to Royal Purple oil. It helped but i'm still not happy. I took off the flowmasters and I run cat back no muffler. Do you guys think there might be a problem with the cat? I would hate to spend the money to get a new cat and that not be it. Any advice would help. Thaks