What are to two codes are you getting?
For a P0401 code; it's the EGR VSV most of the time. Cost me a $1 at the salvage yard to get another one. When this little valve gets sticky, it will give you the " nsufficient egr flow". It's connect by two hoses and one wire plug. With a 10mm socket, u-joint, 10" extension, racket, and the front wheels turned to the left; it took me about and hour to change it. A short drive and no codes
Here the pic of the EGE VSV (red arrow) on My Gen 4.5 5S-FE. It is behind the engine under the intake manifold.
Also, here's a DIY for a P0446:
DIY : P0446 Charcoal canister VSV replacement
It could be a number things without the codes.