Chevy Lumina Engine Hesitation

I own a 1999 Chevy Lumina LTZ with 120k miles and in great shape. I bought it new and have driven it hard from day one. About 9 months ago give or take, the responsiveness / acceleration began diminishing to a point now where it is very noticeable. There is no check engine light, therefore, no codes to go by. I have had it looked at by a local trusted mechanic as well as a Chevy dealer and they cannot seem to pin point the problem with certainty. As I give the car gas as you would to accelerate quickly, it responds slowly and it makes a ticking sound. It struggles going up a hill as well. I have kept up with all maintenance. I did some on-line troubleshooting, which suggested certain solutions such as replacing the air filter, spark plugs and fuel filter, but all have been changed recently along with the starter, battery and alternator. Items suggested that have NOT been replaced are (or not that I am aware of): ignition wires, distributor cap or rotor, ignition module or catalytic converter. Both the mechanic and the dealer think that it could be the catalytic converter, but don?t seem to have a way to know for sure and it?s an expensive job (or so they are telling me) for a vehicle worth less than $2,500. While the new car deals out there are phenomenal, I like the car and could do without car payments. Has anyone else experienced anything similar or would suggest an alternative solution? Happy New Year!!!

Well, changing the spark plug wires, distributor cap and rotor are a good idea. Just the diagnosis of these parts, to see if they are faulty or not, costs more than the parts.
Another good, cheap idea, is to use MAF cleaner, and throttle body bore/plate cleaner. DIY for under $20.

How about using a vacuum gague to test the cat? have fuel pressures been checked under load (tape a fuel gague to the windshield backwards so you can read it while driving)

Hey did you figure out what made your car slow at take off cause mine is doing the same thing