Reports to target list

Hi everyone, 

I am trying to export a report into a target list for a large volume of contacts in order to complete an emailing campaign.

I am have been unable to export more than 160ish contacts from the report to the target list out of the 8000+ in the list.

   I have increased PHP memory as mentionned in the sugarcrm help - no changes.

   I have tested with smaller batches to export from the report to the target list - no sucess

I am currently out of solutions and in need of an idea, 

Anyone with a similar experience here? 

I gladly share more details if need be.

Cheers,