Dreaded P0026 Code- 2010 non-turbo

[LBell2380]

I have a 2010 Impreza Outback Sport with 100k miles on it. I just recently replaced my battery and not long after I got the P0026 code. I first checked my terminals and made sure everything was tight and they are, so it shouldn’t be a grounding issue. I then replaced the oil, along with the oil pressure sensor (passenger side) which did not fix the issue. Next was the VVL Solenoid, which I replaced with an OEM one from Napa. The code stayed off for about 5 miles until I let off the gas and the same p0026 code was thrown. I am not sure where to go from here. Any help or suggestions would be greatly appreciated.