I, too, have real problems with getting mechjeb to run with the new gimbaling action going on. It wobbles 100% of the time, even when flying straight in space, when it didn't do before. Same rocket, just the mod changed. This is true for my delta IV and my delta IV heavy, with roll turned on and off etc. I'm not sure, if it's a mechjeb problem or a gimbal problem. But it keeps me from trying to get rockets into space. (and to the guy that complains about mechjeb - I am NOT going to do a 4 + 9 minute orbital insertion by hand).