Been getting a check engine light blink and what I think is a misfire when I step on the gas hard. Feels the engine has a misfire and rumbles for a few seconds.
The vehicle has 127K miles.
Last week it stayed on and we got a P0420 code. Think we could use some new plugs but wonder if the misfire is caused from a bad coil. Then it dumps fuel in the CC and we get a code. Make sense?

Thanks

 

It could be a misfire dumping extra fuel into the CC, but it could also be the CC is starting to collapse inside causing back pressure that will make the engine feel weak when it's is under load. If you had a coil going out you would likely get a code about that as well. Do you know if most of your mileage is city/idling or highways? I would check your plugs, seafoam the top end and the tank and go from there

 

What ended up being the issue on this if you remember? Sounds family to my post I just made and about the same mileage.

 

I would replace plugs first. These motors burn up plugs faster than expected.