Camry surges and lacks power when going up a hill. What could be wrong?

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Camry starts easy and runs well at idle, however, when climbing a hill it wants to surge w/o power and stays at a 20 MPH speed. I noticed the pipe running from EGR gets very hot. The rubber hose running from the EGR to modulator burnt off. My diagnostic code is PO401. What does it sound like? I disconnected the exhaust pipe from the cat burner to determine if the cat burner or muffler was plugged. Any suggestions?