exhaust glowing

[Destroyer000]

99 ranger 4.0 has mini cats on y pipe and normal cat. no check engine light runs great gets 17-18 mpg. i just did a head job on it friday. ordered new heads from Alabama cylinder head. mine have been cracked since i bought the truck 2 years ago. so i decided why not order up some headers while iam in here.. i picked up some pacesetter headers from summit. i powder coated them with high temp coating and then i wrapped them with header wrap to cut dow on some under hood temps. i noticed if you get on it for a few mines about 10 or so if you look at the passenger side header theirs a tiny gap i didnt wrap and you can see cylinder 2 tube glowing . if it idles its fine.. i know my cats are not plugged and the truck is running as it should with no lights. my guess would be that the wall of the pip is thin, and the way it is chambered into the main collector, its just getting very hot in that one area? . driver side looks fine . ive ran a set of headers before on my other truck With out header wrap and it was still fairly toasty under the hood. what do you guys think my issue is?

 

[Rowdy Fitzgerald]

The first thing that comes to mind for me is it's running lean on that cylinder. May be a dirty or malfunctioning injector.