99 Monte 3.8L Will start, but won't stay running!!?!?

thing starts ok so battery, starter is good but immediatly drops rpm's and stalls, tested the coil packs they seem ok only 40k...i can keep it running by almost flooring the gas but it wont stay at idle...when i'm doing this it sounds like theres cyl misfiring, and its making a loud sucking noise up front....air filter and intake air sensor is perfect....ANY IDEAS??!? Please help!