Welcome to the site. We just had a discussion about cooling issues. Here is a link to that thread: http://www.toyotavantech.com/forum/s...rom-Vancouver-!

Much of what was outlined there applies to you. I didn't discuss head gaskets (that was part of the 10% I didn't discuss) but it is a possibility. Does any coolant blow out your overflow before the temp gauge hits 75%? Does it lose any coolant other than when it overheats? Is there white smoke coming from the exhaust? Can you smell antifreeze at the exhaust when the van is running?

Pull your spark plugs and inspect the electrode areas. They should all appear the same. If you have one that's noticeably different (beat-up looking and/or super clean), that's an indication of a mildly blown head gasket at that cylinder. Tim