As above.

What parts of a car, mechanical or electrical, determine how sensitive the throttle pedal feels? This is for a car with a throttle cable, not drive by wire.

Apart from a slipping clutch is there anything that can make the throttle bite feel like its going out of sync with the transmission?

 

Friction in the throttle cable, spring rate on the throttle quadrant/throttle body, interaction of the throttle position sensor with the throttle and the ECU, reach of the pedal, any dead travel in the pedal, size of the throttle plate which determines how much air is flowing when it's just cracked open on light cruise, whether there's an idle bypass system. That should get you started.

If it feels like you've got a throttle delay, try the TPS.