2012 tacoma shimmy/shake during left turn

hey guys,
I've had this problem it seems for a while, but now seems to be getting worse. I'll run you through the details...
This is a 2012 tacoma trd double cab, 6 cyl 4.0 w/ 4 wheel drive manual trans. I bought it from a dealer as is, and as is came with a 2 inch lift.
The issue is whenever I start the truck and pull away, especially when I am turning left, (happens a little going straight and right), I get this fairly serious shimmy shake. I could compare it to what it feels like when you try to use 4wd on pavement. it sort of jerks forward. Now, this only seems to happen for the first few minutes of driving. After the truck warms up and/or I've driven it for a while, it seems to go away. Until the next time, where it was sitting for a while, and it does it again. It started out with what I thought to be just a glitch with these 6 speed manual transes, as it seems others have this same problem and it just goes with this truck. But it seems to be getting worse, so I am concerned. I've rotated the tires and still does it. I believe I am still under warranty, but I've brought it to the dealer before and would really like to avoid this. Typically I go, loose a day or 2 of waiting only to find out they noticed the problem but couldn't figure out what it was. This happened with several issues, all of which people seem to know what I'm talking about here on this forum, but the dealers treat me like I'm trying to BS them or something. Anyway, any help would be much appreciated. I wanna take it in to my mechanic but have been so busy I really can't afford to loose a day or 2 right now to look into it.