I bought a used 1985 Civic in June of 2008. After riding through the neighborhood enough to keep the battery charged, I finally got a license tag and refueled it for the first time this November. Five minutes after leaving the gas station it reved up to 3500 RPM on its own for 20 seconds and stopped running. Afterwards it woundn't start, but it turned over many times. Adding small amounts of starter fluid to the top of the carburator didn't help. I used a store-bought spark checker and could see good spark. When it reved up, it did so smoothly as though it suddenly got easier to run. It didn't jump around irratically. It has 140,000 miles. I didn't hear any noises or thumps. What's going on?

Perform tests, in Sections A and B, below:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-46563.html