What do codes ATTCP & P0420 mean?

Question

Losing power on even slightest of hills. Rpm's rev to 4500 or so till I let off the gas pedal.

Answer 1

ATTCP is related to trouble codes. P0420 is catalytic convertor below efficiency, When your vehicle looses power on the slightest hill this can mean a plugged exhaust system or plugged catalytic convertor, A plugged catalytic convertor yes you loose power on acceleration or a slight hill, But the RPM will not rev to 4500. So this kind of leads to a transmission concern. a slipping transmission the engine will just rev and there is hardly any movements, Check to see if any P07XX codes which are transmission code are also set with what you have.