Intermittent missfire at low RPMS

[AlphaZulu]

Hello all, I bought a 2017 Tahoe SSV recently with the 5.3L L83 engine. While towing a few months ago I began to get significant misfires and a P0303 code, but only when under load at less than 2,250 RPM. After finishing that trip by keeping the RPMs higher, I changed the oil and on my next trip I got misfires and a P0307 code consistently when under load at below 2,250 RPM.

What would you consider a good starting point for diagnostic? The vehicle has about 91k miles and had the transmission rebuilt at 53k.

Thank you for any assistance.

 

[AlphaZulu]

I guess since no one has any insights I'll just do plugs and wires and see if that helps. I was hoping to avoid the mindless loading of the parts canon, but 91k is probably fairly reasonable for the plugs and wires anyways.

 

[Tahoe14]

@Doubeleive, @Fless, @OR VietVet

 

[OR VietVet]

Because of the mileage and the known misfires on cylinders #3 and #7, I would say you are on the right track. I would remove all plugs and pay special attention to #3 and #7 and compare to the other plugs. I would replace with new plugs and wires. Post pics here of the plugs, close ups of the firing tips and pinpoint #3 and #7. How do the wires look, too. You likely have no idea how much idle time is on those plugs and wires, since it is an SSV.

https://www.rockauto.com/en/moreinfo.php?pk=13869485&cc=3434402&pt=7212&jsn=956

More Information for GM GENUINE 19431551

 

[Doubeleive]

at 91k add a induction service as well, this will help particularity with the direct injection motors

 

[OR VietVet]

at 91k add a induction service as well, this will help particularity with the direct injection motors

Like cleaning the MAF?

 

[Doubeleive]

Like cleaning the MAF?

well that's part of it but the induction service on the k2's involves cleaning the intake valves as well, carbon build up is a known problem usually shows up as a hesitation when accelerating, rough idle, etc. If it's time to do plugs and wires then it's time to do the service also.
this video shows what happens by 100k