ive had issues before with the temp gauge not reading right because the coolant temp sensor had a bunch of corrosion on it. check to see if its got corrosion built up on it. as for the glowing manifold
![In The Dark :inthedark:](https://board.marlincrawler.com/Smileys/marlin/inthedark.gif)
sounds like a lean condition or an exhaust restriction. did you check your muffler also? hope this helps