Just started noticing this recently with my car. If I'm driving up a significant hill on the freeway in 5th gear and I try to accelerate, the throttle takes a couple seconds to do anything. RPM's don't change for that couple seconds so it's probably not the clutch. It doesn't hesitate on flat ground when I mash the gas pedal either. Car is a bone stock 94 CX hatch. TPS maybe?

 

No one? Do I need to give more details?

 

Downshift.