When I try to add text to existing pdf document while typing the text it starts stair stepping the letters up then down. I would appreciate any information.

Hi arrowhead542 ,

Please provide the exact dot version of the software & OS installed at your system .Also check whether is there any update available for the software after going through "help > check for updates "

Follow this thread to reset the preferences for the Acrobat software  :- How to reset Preference settings in Acrobat.

Is this happening with this document only or with others as well.

Would request to recreate the document & then  check for the same .

You may export this document to '.tiff' format & then export that '.tiff' file into pdf format again & then check for the same,

Regards,

Yatharth