Sorry for my noisy posting yesterday, my eagerness got ahead of me and I did some bad testing. Right after I made my last post I crashed yesterday after I had completed several touch and gos, which had not happened before, so I started testing everything a bit longer to see what would happen.
After a few slightly more involved tests, I am starting to become convinced again that it might be the 3jFPS FlyWithLua script after all. I was doing kind of a binary search with enabling plugins yesterday to quickly narrow it down, and I was pretty sure it was either autogate, the simtoolkitpro plug