88 mustang with glowing converter

Can anyone help? The cat. converter on the left side is glowing. I have changed both of the coverters on the left, checked the valve pressure, and changed the fuel injectors (tune up also... new plugs, plug wires and cap) I don't know what to check next. Any ideas?

Is the car running poorly? On my VW it was not uncommon for it's single cat to glow after i ran it hard. It was't cherry red, but you could definitly see it glow, no matter what the light conditions were.

What year is your car. Do you still have the smog system intack, are the O2's new?

What year is your car. Do you still have the smog system intack, are the O2's new?
This is a 1988 GT 5.0 conv. This car is from california. It still has all the orginal smog system. The 02's are not new, but when I swapped the right one over the left still glows. (the right cat. conv does not glow) The car runs and idles fine. Is it possible I have a computer problem? The check engine light is not on.

Well, the cat is clogged for some reason, the only fix is to replace it. For some reason, weather it be you were running rich for a while, bypassed the smog pump, or a multiple of other things could result in it's demise, especially if it's original equipment from 88.

If you already put new converters on and still have the problem maybe you have something clogged between your converter and tailpipe. Have you checked the tailpipe for a banana? If you had your distributer out you may have it off by one tooth causing your timing to be out of whack.