i have a pretty serious lunge, but only when the AC is on and i'm stopped...or slowing down.
if i stop suddenly, about 3-5 seconds after i stop the car tries to lunge as (i guess) it shifts down into low gear. i'm stopped, so the brakes keep it from rolling. but it def tries to lunge. and on very slow stops, you can feel the car lunge a bit as it down shifts to each gear. i thought maybe my rotors with warped, but they have been replaced and it still happens.
it's hardly noticeable if the AC is off. but with it on, you can definitely feel it! the toyota techs have said it's just the AC cycling on/off.
one final thing, the engine idles VERY high when it's fist started. if i start it, put it into reverse, the car really goes. maybe it's normal, but for what it's worth, i didn't have these problems with my 2002 Sport Edition. (which i sold to get the 2005)
i saw the posts about the tranny "learning" your driving style. i bought the 2005 Limited with ~40K on it. so i thought i just needed to unhook the battery for 15 mins to reset it, but maybe that's pointless???
i love the truck and that's the only issue i've had with it. clearly, the OP has some concern since his is brand new...not to mention the other issues. i'm sure you're probably just waiting for something else to come up. sorry man. 4Runners are incredible trucks...hate to hear that someone is having a bad experience with one.