purge flow error need help this is what i have done so far

replaced rubber line to charcoal canister
replaced gas cap GM new
smoked vacuum lines no leaks
cleaned vacuum line from pvc valve to air cleaner resealed connection on top of intake
replaced purge solenoid
replaced charcoal canister

any more suggestions?

Will the tank actually pull and hold a vacuum? You'll need a gauge and pump, or the ability to operate the purge line vacuum solenoid valve.