Theres a picture of your fuel rail showing where things are located. If the pressure regulator wasnt sealing when the engine was shut off, fuel would bleed off into the return line and make for hard first of the day starts. Depending on the amount of time the vehicle sits would go hand in hand with when the problem occurs.

Since rereading the top of this thread where you mention that the hardstarts seem to happen more as the tank level drops, Im wondering if your EVAP system is partly to blame?
Check the condition of the fuel return lines, charcoal canister and all related hoses and vac lines...look for something that just dont look right.

I dont know much about the 3.0L at all, always been kinda skeered when lifting the hood on a V6 Yota...now I know why!
I'll get some links together shortly and see if they help at all.

~Darin <img src="/forums/images/graemlins/baby.gif" alt="" />