I'm legitimately surprised this hasn't been posted yet. http://www.angryanimator.com/word/2008/11/01/animation-tutorial-2-walk-cycle/ Best walk cycle tut I've ever read or used.
i like the new pose! biggest thing right now is you have to slam his feet down alot sooner when they hit the ground. i usually do 3 frames after the heel hits, the foot is flat. 2 frames for running.
Have you checked the graph editor to see what the problem with the infinity loop might be? You will probably see something wrong at about 25 frames(I'm guessing that's how long your sequence is), 2 identical frames or something. Your animation looks good, I guess you've only worked on the legs and not the upper body? You…