My '06 V8 service manual says that P0102 is a problem with the Mass Air Flow (MAF) sensor. It's located along the air intake duct. P0420 and P0430 are complaints about the catalytic converter working inefficiently.
I'd bet that the cat codes are side-effects of the MAF sensor problem. The MAF sensor is notorious for aging and then appearing to cause other problems on Toyota engines, so I'd start there. The MAF is made with two tiny little wires as sensors, so they eventually get dirty and don't work right. If you use an aftermarket air filter, you need to make sure it doesn't have any oils in the fabric, as the oils will collect on the MAF and cause it to fail prematurely.
The MAF can be cleaned very carefully with electronic cleaner. A search will probably turn up an exact how-to procedure.