As you probably know, that #44 Solenoid (fuel tank breather) valve error relates to the small solenoid that is mounted in a rubber holder under the intake between the CCV and and the oil filter housing. From memory, it has two vac hoses and an electrical connection.

Check all those connections. I had this error recently after a head gasket job. One of the hoses was either dis-oriented and would not click into place or was broken causing a bad seal. I also swapped in a new or used valve. The error went away.

I don't know if that is the source of your mis-fires