If the intake manifold is not tighten correctly, would this cause the exhaust manifold to turn red hot. Would it also cause the engine to run at a high rpm.
In take manifold on 1995 Jeep Cherokee
An intake manifold that is incorrectly tightened and allows air to be drawn in past the intake manifold gasket (causes a vacuum leak can give a high or erratic /surging idle speed and cause a misfire. If the vacuum leak is so severe that it causes the engine to run "lean" the exhaust manifold could get red hot in theory and power would suffer.
It would also send fresh air to the Oxygen sensor which would make the computer set the mixture to full rich would would heat up the manifold, even to a reddish color.