surges at idle exhaust glowing red

This car (is supercharged) over heated and shut off. Diagnosed a blow head gasket and replaced it. Took the head to a machine shop and had it resurfaced and the valves ground and reset. Put it back together and found out the supercharger was making lots of noise and the idle was surging and exhaust glowing. Replaced the supercharger and now the supercharger is better but still have surging idle and red hot exhaust. I disconnected the catalytic converter and still the exhaust is glowing and surging idle. I would think the injectors leaking would cause the fuel to burn in the exhaust manifold but there did not seem to be any issues with this before the car over heated. I am stumped as to the cause. Any ideas?