The actual three steps process of creating, editing or saving as new question use $SESSION to store data between the steps.
The most crucial problem is that when creating a new question, the saving of question parameters is postponed to the third step until the user add a first dataitems. The proposition is to save the parameters at each steps so that if the user does not complete the process, what has been done is not lost.
A mode detailed analysis is available at
http://docs.moodle.org/en/Development:Calculated_question_bugs_and_new_features_proposal
A solution has been tested and could be implement on 1.9 even 1.8 as it does not imply new database features.
The necessary files will be available soon on
http://moodleuqamchi.cvs.sourceforge.net/moodleuqamchi/moodle/
and as attachment here