2013 1.8L Runs rough - replaced cracked air duct - not fixed.

Hey there! My wife and I own a 2013 Sonic - AT 4dr 1.8L w/ ~33K Miles. CEL IS OFF

A few months ago the vehicle began to develop a sporadic rough idle. I was informed by the dealer that they recommend the air filter and fuel system service around 30k (contrary to the service manual) When I changed the air filter I noticed that the factory air duct running from box to throttle was cracked and in shambles - just raising it to replace the filter nearly ripped it in half. I remedied this with a factory replacement of duct work and air filter, also performing the fuel/air service (seafoamed fuel, and cleaned MAF + TB with appropriate CRC sprays).

This has not corrected the issue in the slightest, it continues to worsen. Rough idle and rough under throttle. All pulses are random and not consistent - vehicle can be driven without major issue unless it is very hot or for long periods / distances. Shifting to neutral reduces severity of vibrations, but can still be felt - so obviously it is indeed a motor issue) When stuck in traffic or at outside temps over 80 the motor wants to idle <500rpm or stall. Running AC compounds the issue.

I am at a loss, any suggestions / advice are welcome and appreciated.

Hi BigMoCotton -

Not to chase you away, but you might have better luck on a dedicated Sonic forum. There are a couple.

Who do you recommend?

I'm not really familiar with them, but if I had to pick, I'd probably pick the one with the largest active membership. And one with a "troubleshooting" sub-forum.

I'd Google Chevrolet Sonic forum and go from there.