2002 chevy cavalier 2.4l twin cam auto 4door

Hi there, iv been working on this car for past few weeks. had everything sounding great and all codes cleared, Left it sitting for 2 weeks tried to start and no go.
iv tried..

batery boost.
cleaned battery cables.
bench tested starter. (good)

it cranks over really slowly and wont start... could it be a ground conection? What are my options here? im stumped.