Well if the pedal sticks or is hard to press after a while, you might want to check the small 6mm or 8mm adjustment "stops" for the throttle plate. This is the stop that actually stops the throttle plate. Move the throttle by hand and look around for what is actually stopping it when you close the throttle. This can be adjusted and if it is set to far back, then the throttle plate would get wedged in the throttle body and it would take some added force to crack it open again..
You want it to close completely, but it needs to have a smooth and free opening when you open it back up.
Try this: With the engine off, pull the throttle all the way open (WOT) with your hand and then let it snap back closed as hard as possible. Then try to open it up again. If you have to nudge it or give it more force than say if you were to open it and gently close it by hand, then the stop screw needs to be moved closer to the stop on the throttle plate arm.
BigMike