My experience with a glowing manifold resulted from a lean burn condition caused by faulty rrfpr but that was with a turbo. The other cause, as mentioned before, is a plugged cat. The latter is the more common cause of a glowing manifold. I've been told that you can check if your cat is plugged by using a laser thermometer, you take readings at the front of the cat and then at the back. A well functioning cat will have a noticible temperature difference whereas a plugged cat will have a uniform temp. If it's not your cat then check your fpr, fuel filter, fuel pump....etc...


Good luck