Why does my car lose power going uphill?

Climbing hills puts maximum load on the engine, so any weakness shows up there first. A clogged catalytic converter is the #1 cause of 'I have full throttle and the car still won't pull this hill' — the exhaust can't escape fast enough. Other suspects: weak fuel pump (can supply 10 psi but not the 50 psi the engine needs at WOT), failing turbo (on turbo cars), or clogged air filter starving the engine.

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