408 still overheating :/

I haven't seen any mention of the electric fan cfm. I think they need to put out close to 4000 cfm. Correct me if I'm wrong. And doesn't the underperforming electric fans become an airflow obstacle? What did the shroud look like? If it's tje type that's a shallow box with just a hole for the electric fan, they are also an obstruction. Put a mechanical fan blade, and shroud on it first. Mine was 18 inches in diameter. Then make sure you have a hood to core support seal. It keeps from pulling the hot air back in. Almost 95 percent of the time when i read about an over heating issues, an electric fan is involved.