Thank you for this thread. My 2002 Avalon was exhibiting the same issues, dying immediately after cranking and having to hold the accelerator down until the engine warmed.
The entire process took me 1 1/2 hours from popping the hood to go-jo on hands. I took the cover off from the 2 throttle bodies as suggested. It was easier to replace the right TB after cleaning. The most difficult issue actually was removing the hoses from the TBs. The old screw issue I had was with the TB cover. I disconnected the 2 electrical connections (one on the IACV and other on the TB) and then removed the right throttle body. I then removed the coolant hoses as it was easier with the body removed to access the clamps. The IACV magnetic cover was removed, found the 'wrinkle' washer. Removed the 4 screws that held the valve to the TB. I was able to save the quick tie that held the electrical cables by inserting a flat blade driver in the slot and pulling the strap out.
I cleaned the entire TB and valve and had the idea to use my dremel with some flitz polish to smooth out the casting marks on the valve where it feeds into the TB. Wasn't necessary, but I was into removing all gunk. I thought about removing the left throttle body to clean it, but after seeing the cabling and throttle controls I had a moment of clarity. I did clean out around the butterfly valve and intake. It went back together in reverse order and fired up. Idle had been running about 1100rpm never settling down below 1000rpm. After the cleaning it ran around 1200rpm and I took it around the block. After cranking about 4 more times, it has settled to about 800rpm in park and approximately 750 in drive.
Thanks to everyone that contributed and added their tips.
