i took my car out on an empty strip of highway, slowed to a stop and flored it... it got to 2nd then stuck till it hit red and i let off the gas... but it didnt shift till i let off the gas. why does it do this?? how can i fix it?

P.s. its automatic

 

are you shifting through the gears?

 

I would start with the basics. Fluid/filter change. Drain the torque converter too...