weak minivan

my van lumina apv 3.1v6 lurches when you try to start out unless you hold the gas pedal down to just before the kickdown point where it pulls like it wants to race;if you push it all the way to the floor it doesn't lurch or surge , it just falls flat on it's face until it revs up,and then it still runs stronger if you back the gas pedal off to it's sweet spot. if anyone can haelp me I will be eternally grateful. thanx in advance, Jarrod

Very first thought: Throttle Position Sensor is bad. Next thought: maybe.