Mailarchives (A86: Still can't figure it out. Also, FP stack?)

Well, my program is back to where it was before it started acting REALLY goofy. There's one thing that I still don't get, though. If you run this program (be patient, it takes about 5 min to run) you'll notice that the X values start to repeat at about the 100th column. It really confuses me because I can tell that Xcounter is not getting reset because it continues plotting to the right, but it's like the program picks up previous Y values. Any ideas about why this would happen. Also, on a very different note. How do you push and pop a value, say in OP2, onto the floating point stack? Thanks for the help!