"Replacing a car isn't an option, there has to be something that will kill the acid."
Free oxygen in the atmosphere will neutralize the acid. You could:
re-apply with Ospho
first rinse with 'sudsy' ammonia and water to neutralize
second rinse with clear water until clean
heat the panels above room temperature
moisture condenses on sheet metal exactly the same way as an iced-tea glass and autobody products are petroleum based, they float on water. You really do need the get the moisture out of the pores of the metal if you want the job to last.