2005 Chevy Impala that sputters under heavy acceleration/load. Throwing code misfire 6th cylinder. My thought was spark plugs, changed them. Still threw the code. The idiot light also will flash but if you lay off the gas and sorta feather it the light will stop flashing. Most times it is north of 40 mph that the light will kick on and flash but it will also sputter under 40 mph. I am now thinking coil or mass air flow. However I could be missing something and wanted another opinion or ideas.
You need to find out what’s causing the misfire.
A flashing Check Engine light means a major misfire which can result in damaged/destroyed catalytic converter(s).
Here is something that has me confused. See if can understand this. It showed a P0306 the 6th cylinder misfire before and after spark plug change. Diagnosing the possibility of a bad coil I took 6th and swapped it with the 3rd on the coil. The P03006 went away but a P0300 came up instead. Is it the coil or possibly spark plug wires? Could a short in the 6th wire shortage the coil pack that causes both 3rd and 6th coil to fail.
If you don’t know the last time the secondary ignition components were replaced, that’s where I’d start.
This includes coils, and wires.
I mean, those components are 16 years old.