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Well yelling and cursing is only going to make the neighbors mad so try this info. The problem 90% of the time is the VSV on the charcoal canister. They are notorious to go bad especially in the northern states. Click on the links below for some exciting reading that you will be able to brag to your buddies about knowing. ha ha I also posted a TSB for the 99 Corolla ECU problem that sets a P0446 I don't know if it applies to the prizm or not but you can check it out. The second download will explain the system a little just to make you dangerous. If you would like more exciting reading let me know and I can get you a link with the complete evap systems and break down on the operations.
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The DOWNLOAD buttons are just links to the PDF files. If you have adobe they should work if you click on them. I just checked them. Try the 2 links above for the files on a file server try downloading them from there and let me know if you can get them.
Good luck, I am not 100% certain that the prism is the same on evap as the corolla but you should be good to go.