what is the towing capacity of the 1992 astrovan??

i have a 1992 astrovan tiara edition awd.  the 4x4 has been disconnected as it was no good.  i need to know  what is the towing capacity of the astrovan?  i just installed a hitch..  and i tried to tow my trailer which is around 3000 lbs.  the rear of the astro was about 6 inches from the floor.  i decided not to tow it.  i was told by a mechanic  to rebuild my springs and add more springs too the rear suspension.  will that help?  he said the added springs will give the suspension more strength.  what should i do? can somebody help me with this?  i need to tow my trailer to work and back everyday about 80 miles each trip.. 160 miles daily.  am i going to be able to pull it off or do i need a new truck??? please email me to pilots113@aol.com with any answers to these questions asap.  thank you very much