Hyundai Santa Fe & Pontiac G6 Not Accelerating

Question

So my Hyundai Santa Fe 2011 is having issues accelerating during the 10-20mph. Once it's over 40mph it's easier for it to get faster. If I press the pedal when it's barely moving, it makes a noise so I've been pressing it slowly to get up to speed. Does this have to do with the throttle position sensor or the catalytic converter is bad?

 

Also with my Pontiac G6 2006, it is having issues accelerating.

 

 

 

Thanks for any input!