Other Fuel System Tank Mounting problems of the 2003 Toyota Tacoma

My truck was part of the frame recall and I had the frame replaced in 2010, since then I have had to pay to replace other rusted parts that were not "part of the recall". First the spare tire mount rusted off and the tire fell out from under the truck while driving. Next the entire exhaust needed to be replaced as it too had rusted out. Last year to pass inspection I needed to pay $1600. 00 for a catalytic converter. This year I cannot pass inspection as the check engine light is on and despite 2 attempts to find the problem (and $200. 00 later) the light remains on. The suspicion is the gas tank is rusted "at the top" and will cost me $1800. 00 to replace. I just received a "preliminary" recall for the spare tire mount, I imagine I will receive a recall notice in a few years for the gas tank as well. Ridiculous that only some parts were recalled. . . And ridiculous that I have to pay to replace the others. . . Not to mention the inconvenience.