honda uses brass syncros in thier transmissions, and the one golden rule i have learned with honda transmissions is ifgoing to replace 1 synchro, replace them all, if not and GM synchromesh (its not a fix, its more like a band-aid(if pat was still around, it loves the stuff.)) also your camber is way out of line, and its really bumpy because of the coilovers(and your probably running a stock suspension, with just the coilover's right?)
also if you haven't checked out
www.honda-tech.com check them out, they have about a billion more members than we do, and will help you out alot more than we can. now that i think about it, only one person on this board has the minivan, i mean ep3. alot of good parts can be had on ebay, just make sure you research what you want before you order.