Q: At highway speeds, car loses power

At highway speeds, my car experiences loss of power. This problem is intermittent and it has been serviced “five” times; however, the problem continues. The engine is making a ticking sound and there is a power drop of about 35 mph. The dealership replaced the fuel filter, fuel gauge, O2 sensor, and the fuel pump. This most recent service trip, the dealer insisted that the problem is a clogged catalytic converter. Losing power on the interstate, or anywhere, is very serious and dangerous. Plus, continually being told by a dealer five times that the problem has been fixed, when it isn’t, is very frustrating. What is your diagnosis and solution?