I have a 2000 Nissan Frontier with approx. 160k miles. When driving home from work two days ago, it suddenly began to mis-fire and lose power. I limped for about a mile at 30mph or so, but eventually pulled over as I was steadily losing speed. The passenger side catalytic converter was red-hot. Just some background -About a month ago, I replaced a faulty injector - it had been bad for about a month - I supposed that running the truck with a mis for a month dumped unburned fuel into the cat. And that made it fail.
I assumed the cat. Was clogged, so today I replaced it and the exhuast manifold(had been cracked for years). I also replaced the O2 sensor that is upstream of the cat. Upon inspection, the old catalytic converter was melted inside (honeycomb broken apart) and I could not see any light through it when I held it to the light. After replacing the cat. And exhaust manifold, I cranked the truck and it ran fairly well (slight mis) for about 3 mins, then began to idle very erratically - if I pushed the accelerator to wide-open-throttle, the engine would mis and there was some pinging that came from the exhaust. It would not rev above about 2500rpms.
To attempt to fix this problem I have:
Replaced distributor cap, rotor, plugs, plug wires and fuel filter.
Tested and inspected the MAF and EGR valve.
There are no codes and the CEL is not on - the only code I had when the truck broke down was for a bad O2 sensor (which was replaced along with the cat.)
I have also inspected all vacuum lines and can find none that are loose/broken/leaking.
I'm losing my mind trying to figure this out -- any help would be greatly appreciated