Kevin did not show his emotions in almost every episode of the series. Was the 1st season episode 3 where he wants to go to work with his dad the only episode where he is crying?

I'm pretty sure he shed a tear whilst working the Stage Spotlight at the end of Winnie's performance in the School play "Our Town".

There was another episode in Season 4 where Jack (showing a rare glimpse of his softer side) comforted Kevin in the garage after Winnie hurt him at a party.

Yeah I remember he cried few times in the on the spot and the episode denial episode, but it was rare to see Kevin in a emotional state of mind.