Red hot exhaust

I have an 01 Ford ranger with a 3.0 six cylinder. The passenger side exhaust manifold got so hot it melted the housing around the a/c evaporator. The local dealer said both converters need changing for a mere $2400. Took it to a local muffler shop where did a test and said they were ok. But it still doesn’t want to run and the muffler guy unhooked the exhaust from the manifold and it still wouldn’t run so he said. And to me out looks like 5 converters not just two.

If the manifold got red hot, (the manifold is not the converter) then something else is seriously wrong with this engine. Exhaust gas temperature climbs if the engine is operating in an over-lean condition or UNBURNED fuel is escaping from the engine into the manifold where it ignites and burns…This is a fuel delivery or valve problem, not a manifold or converter problem.

Yes, @Caddyman. Also, retarded timing will cause the exhaust manifold to overheat.