I have a 1985 RX7 12A (GSL) stock with manual transmission. I been have problems with it loosing power after it warm up. Today, I test drove it for about 10 minutes and after the test drive I notice the exhaust system after the exhaust manifold was bright red hot at 11:00 AM in the morning. What could cause the exhaust to heat up like this? .

 

Had a bad lower intake manifold gasket that caused a high idle as well as a glowing red exhaust manifold.

 

i had the same thing happen on my fd and it ended up being a broken spark plug. the shell of the plug was broken. it was hard to diagnose since the plugs were brand new and it drove perfectly fine otherwise

 

Guess....clogged cat

 

Can I delete the Cat and two Pre-Cats? Will the car run ok?

 

Try advancing the timing and see if it goes away.

 

Do you have more history on the vehicle? Did you buy it like this, was it running just fine and then this happened, or did someone work on it and now the issue is happening?

The engine is likely running too lean due to timing being way out or the cat being clogged.

 

as someone already said , a trailing plug that doesnt fire (either because of bad plug or plug cable or faulty coil) will raise egts (+200C)
that will make your exhaust glow