Transmission problem or exhaust/catalytic converter? Jeep struggles to go up hill, RPMs shoot up.

Automatic 2.5L engine. Fluids ok. New spark plugs/wires and distributor cap (6 months ago). New oxygen sensor (2 months ago). Car struggles to go up hills. RPMs shoot up but car does not accelerate. Also when I try to accelerate quickly, as when taking someone over, I cannot do it. RPMs shoot up but the car does not really speed up much and the engine just revs. Problem started after a long road trip (3 weeks ago). No weird noises from cat converter. Exhaust is kinda loud already but sometimes smells now. Driving on flat road is ok as long as I keep the RPMs around 2 or below 2.5 - anything above that, RPMs will just shoot up. Somewhat of a rough idle when in park. No back firing of exhaust. No problems in automatic downshifting of the transmission like when I stop at a stop light. Please help!