If it won't hold, that tells me that something is worn, bent, or broken. Do the techs tell you what is out of spec and what they do to correct it? Also, is the rear alignment holding? I know on the Gen 5 Camrys that the front lower control arm and strut designs were changed between '03 and '04. The guys on toyotanation said it was to weaken the link to lessen structural damage in a collision. I don't know what that does to parts longevity, though. Your Sienna may have a known problem that can be fixed that no one is telling you about. You might check over at toyotanation in the Sienna forum. http://www.toyotanation.com/forum/274-2nd-generation-2004-2010/ Addendum: Reading over at TN, I found a link to a TSB for updated alignment specs for your van: http://www.mediafire.com/view/?odf5fyq5lya5ci2 It's not coming from Toyota's site, but it looks like the real deal. That won't help if the settings move around on you, though.