Red hot exhaust

The misfire could be the cause as excess fuel burns in the exhaust system, Running too rich could also do it.

That misfire at idle and probably all other times too is allowing unburned fuel to enter the exhaust system and get ignited there, thus making the pipe glow red hot. You should change your spark plugs and also check for spark at all cylinders. If it's a coil pack, they will misfire in pairs. If it's a coil on plug system, they can fail individually, maybe more than just one. Scan for fault codes too concerning misfires.

Anytime the exhaust system starts to turn red something is clogged like the catalytic converter or muffler