2001 Suburban 1500 5.3 P0304 flashing SES
 

P0304 drives fine but idles like it has a big cam. SES on and sometimes flashes. I put in a new plug, swapped coil from 4 to 6, and spark plug wire from 4 to 2, cleaned the MAF and cleared the codes.


No change. After a while at idle (like at the end of a traffic light cycle) the SES light flashes until I start to accelerate and then goes out. Scan shows a pending code P0304.


I listened to the fuel injector and it sounds like the other ones on the bank, but I know that won't tell me if it's dirty.


Any thoughts on what to tackle next? I am a bit surprised that I moved/changed all of the spark items on cylinder #4 and it's still on that cylinder.