My E-file keeps getting rejected and I have checked my '18 AGI and I have gone to IRS.gov and verified AGI with my '18 Tx yr Trans. What can I do at this time to e-file?

e-filing is now closed. the return must be printed and mailed. carefully read TT filing instructions and use a mailing method where you get proof of delivery. 

If your efile rejected you still have like 5 days to fix it and refile.  Did you try entering 0 for the AGI?  If that doesn't work you will have to print and mail it.  When did you file 2018?  If it was later in the year then the AGI is not in the right IRS database to verify you so enter 0.