Upon arrival, inspected furnace and found unit in a lockout on overheat. Discussed with homeowner and homeowner in informed me that he has had this problem for a long time with the previous company. They have made many adjustments and have not been able to resolve problem. Upon first inspection found gas pressure at 3.72 lowered down to 3.25. Found air speeds on factory blue setting raised air speed from 1050 CFM to 1200. Delta T went from 64° to 57. While adjusting blower speeds noticed a weird relay fluke where blower motor would not come back on for approximately two minutes. Discussed with homeowner that there may still be issues with the control board, but the furnace has been dialed in and should no longer have overheat problems unless there is a blower motor relay problem underlying. Unit is fully operational at this time.