Truck won't start unless gas pedal is pushed in.

I have a 3rz and the past 2 days I go to leave from work and the truck cranks but doesn't fire. Tonight I talked to a mechanic at work to see if he had any ideas. he said to try and push the gas pedal all the way in. I did that and it fired right up. The truck idles fine once it's running. He said by pushing the pedal all the way in it cuts off the fuel so it seems like the truck is flooding itself when trying to normally start.

Anyone know how to fix this? Can't seem to find much by searching and I know very little about engines.