My recollection is the same as what Trodgor stated. As I recall from skimming the multi-hundred page PDFs relating to the CHI-STL project (available on the IDOT website), some of the project relies upon the findings of a 2003 study when some work was completed on the line. I think there are references to ROD03 (Record of Decision 2003, I believe). Also buried in those pages is IDOT's intention to (likely) raise speeds for the other trains as well.
Essentially, the Texas Eagle and the former Ann Rutledge do not run above 79mph at this time.