1998 Toyota Camry Loss of power after reaching freeway spee

My 1998 Camry, 114000 miles, idles and accelerates
fine but after accelerating to freeway speed and holding that speed constant for about half mile, I feel a loss of power as if the parking brake is slightly on or I just hit some headwind. There is no noise, I don`t notice a drop in RPM, not a big loss of power, it just feels like I`m pulling a load.I recently had the oxygen sensors replaced and it seemed to have started shortly after.I drove about two months with bad sensors and the engine light on, someone said it could be a clogged catalytic converter. Someone else suggested the transmission. Any suggestions would be greatly appreciated. Thank you.