This may be totally unrelated to your gas cap problem, but I'll mention this anyway, so take it with a grain of salt. We owned a 2010 PleasureWay Excel Ford E-350 van, which we no longer own, decided it was time for a newer model PW. We traveled extensively across country this past August and September. We were in Canada and stopped at a gas station to fill up. When we tried to start it again, it wouldn't start, would hardly turn over. After a few tries, it worked and we were on our way. Decided to stop at a Ford dealer and told them what happened, as it didn't happen after that. They suggested bad gas, so suggested we buy at a known brand station. Next time we filled up, same thing happened. By this time we were concerned, as we had a lot of wide open space to cover, with no stations in sight. So we scoured YouTube, found a guy who was leaving his gas cap off while starting up after getting gas, and it would start, and then screwed on his gas cap. That was good for awhile. Then we decided to really find out the cause, so we went to yet another Ford dealer, ran diagnostics, couldn't find a thing. Third time we went to a Ford dealer in Canada, they did diagnostics, found some problem with an evaporator sensor of some sort. They had the part overnighted to their dealership, we had it installed quickly, took at the most 1/2 hour in the morning and we were on our way, and we never had another problem with it. So it must have something to do with emissions of gas fumes, and perhaps yours is due to getting a generic brand replacement gas cap. We never had a problem with it after that.
Betty[purple]:C