Access to Scion repair manual (vol 1 & 2, no electrical)
 

Just post up and I'll provide what I can find. Torques on anything, capacities, diagrams, etc.

any diagrams of the intake manifold, like cross sections or interior views?

Nothing related to the interior of it at all...

hmm...

anything about a timing sensor and/or its adjustment located near the crank pully?

balance shafts?

There sure is, if I remember right from paging through it. I'll take a look at it and ask you what you want to see from what I have. Probably Monday or tomorrow night.

okay cool... i havent seen the sensor myself, but it should be on a sliding bracket, so you should be able to just loosen it a little, and you can move the sensor to adjust the timing slightly, usually +/- 2 degrees or so. might be nice to see if that low end could be beefed up just a little bit - i dont use higher rpms much anyway. it should be located on the side or below the crank pulley.

the balance shafts (im pretty sure this car has them) would be nice to take out as well.

You may already know about this site but what the heck. techinfo.toyota.com
10 bucks a day. All you can download in that time. All the toyota technical documentation on the xD is available.

Well, without reading every bit of text in this book, (index is useless in some aspects) I cannot find anything at all regarding a timing sensor. I see timing chain, crankshaft timing gear/sprocket, number 1 chain vibration damper, chain tensioner slipper, and a number 2 chain vibration damper. Nothing at all about adjustment. Keep in mind, it's a chain not a belt. Don't see anything on balance shafts either!