Filtering a form whilst it's opening can be done in the OpenForm command itself. You don't need to pass values all over the shop. To give you flavour of how it's done:
Code:
DoCmd.OpenForm "[COLOR="blue"]FormName[/COLOR]"[COLOR="Red"], , ,[/COLOR] "[[COLOR="blue"]Field1[/COLOR]] = " & Me.txtBox1 & " AND [[COLOR="blue"]Field2[/COLOR]] LIKE *" & Me.txtBox2 & "* AND [[COLOR="Blue"][COLOR="blue"]Field3[/COLOR][/COLOR]] = [COLOR="red"]'[/COLOR]" & Me.txtBox3 & "[COLOR="Red"]'[/COLOR]"