Car loses power going up a hill

Sometimes the air intake hose will pop off because the motor mounts are bad. As far as losing power going up hill I would change the fuel filter and see if it runs alot better.

You say you replaced the air filter, was it really dirty? First thing that comes to mind with this power loss issue is a dirty/or malfunctioning mass air flow sensor, the mass air flow sensor has tiny little sensors inside that can become dirty causing the readings to be off that can lead to power loss, I would suggest you try cleaning the MAF with an approved cleaner, I'm sure it's available at auto parts store. Clean it and retest operation. Other causes could be a restricted exhaust system, fuel pressure or delivery issue. Do you have a check engine light on? If so, get that checked, that could lead us to a direction of diagnoses as well. Let me know.