My honda gx 160 generator exhaust is glowing red

Verify that the double gang circuit breaker is good on both sides. Check for loose wire on breaker or receptacle.

Voltage regulator, carbon buildup in the cylinders, the carburetor may need overhauling, engine governor may have a stretched spring, Spark plug may need replacing, Timing may be off, air filter may need changing, and lastly, your load may exceed the ability of the generator.Checking this list will uncover the loss of power

Restrictive exhaust or catylitic converter

Remove it. Go wide open see if it stops

If it is black smoke, it could be running rich and the correct carb will fix that. If it is blue smoke, then it is burning oil.

I look up honda engines at : honda-engines-eu.com they have the best access to detailed information. If you can identify the carb butterfly, any cable should attach to the butterfly control. I see a Honda GX100, but not a GX31.

check the valve adjustment

Not RED hot, no.
You may have a restriction or a timing problem.
Was it that hot before you replaced the exhaust parts ?

THAT SOUNDS like a VERY LEAN condition. The exhause glowing is because its so lean. The stalling the sputtering. OPEN the gas valve more WHILE its running. With a load if possible.. If you have a tri fuel kit like I do, going from propane to nat gas I need to open the load block (gas valve) 2 turns more .Then it starts and runs great.

try removing the float bowl on the carburator and cleaning, sounds like needle valve is partially stopped up

Go to hondaengines.com and down load the manual you need