Tried fixing some of the joint problems and limb stretching...
By the way, is limb stretching always bad ? I mean we are seeing a 2D picture of a 3D guy, so "stretching" may simply be due to the elbow moving along the Z axis.
Maybe the best way to figure out is to stick red dots on your own joints, place yourself in front of a camera and do an idle stance, just like rotoscoping used to do (given modern digital cameras, it should be quite easier
NB: while typing this, my browser got buggy and start skipping some frames of the animated gifs below, which surprisingly made the character more "real" (despite a more jumpy animation) as he wasn't repeating the same movement again and again. It might worth investigating further