I think I have a failed pressure sensor (N351). When I leave the tube from the engine connected to the sensor, I would have hesitation around 7k rpm and the manifold and downpipe would get real red. However, when I took off the tube to test, the car redlined no problem in the 1st 4 gears and the exhaust manifold and downpipe were not red at all.
Does that mean I am running super rich? If I am running rich, wouldn't it mean that the exhaust gas is cooler hence the manifold shouldn't be cherry red?
Is there a fix for this or do I need a new sensor?
Also, I noticed with the tube off, there were no more back fire when shifting at high rpms.
What would happen if I just ran the car with the tube off?

Sorry for a million questions.

Thanks