OK. If deleting a few variables makes a difference, then I would suggest that you are very close to the limit on your RAM.
One way to free up RAM if you are just printing text is not to use Parola but just the MD_72XX library. The Parola libraries add a bunch of overhead that, if you are not using the animated displays, is unnecessary.
A straight text print example is probably a good one to have for the MD_72XX library. I'll work one out and let you know when I am done. That should make your program smaller and more straightforward.