Your misfire could be throwing unburned fuel into the exhaust system and the catalytic converter. When it gets burned in the cat it may be generating excess heat.
The reason I asked about the O2 sensors is that if they're replaced and the wires get connected wrong (there can be up to 4 separate O2 sensor) it can lead to glowing cats and a confused computer.
The broken ground strap is pretty common and usually isn't a big deal. It's good that your mech caught it and replaced it though.
just a quick overall update...
after mechanic left I had my buddy from the exhaust (muffler) shop run another scan and clear the previous codes and then to my dismay it coded with a p1405 code. I was not a happy camper... I bought the explorer to work out of and its been six months of trial and error to get it to run normally. Mind you I bought it cheap enough and knew I would be putting some money and time into it, however I was getting about to the end of my ropes.
Anyway, I looked up the code and it said (first line) hose for egr unplugged or clogged so we went to look and sure enough the two little rubber hoses were both disconnected.
AND THE GOOD IS... After hooking them on... NO CODES!!!
I wont believe it until I drive it for a whole day and the light stays off. But at this moment I am one happy happy explorer driver. It runs and idles smooth and purrs like a kitten. When I put my foot into it it roars like lion. (well, as much as a v6 all stock vehicle can) floor is staying a lot cooler, gas lasts forever, (comparatively) and I no longer feel the stress of "will I make it to my destination" or will it end up "found on road dead" LOL!
exhaust guy also said that the exhaust "smelled" clean...
I guess he would know.
tomorrow after work I will take it by his shop so he can run an exhaust system scan with a different scanner and if all checks out I can finally get a smog check. Just in the nick of time as my registration is due for renewal next month.
I love my li l red