Try This-
V_Filter=If(UserResponse("Select Plant Name")="Luling Plant" And [Tag Type] InList ("Average";"MACT") )Then 1 ElseIf(UserResponse("Select Plant Name")<>"Luling Plant" And [Tag Type] ="Average") Then 2
Create filter on on V_Filter object and type value 1 and 2, Do not select from list of value of the V_Filter object.