05 lgt rough idle and misfires

[ALASKANSUBIE]

So i have just completed redoing the head gaskets on my 05 legacy gt with the DOHC and after a few minutes of driving the engine light comes on. So, i check it with my reader and it was giving me a p2021 (tumble generator valve position sensor) so i pulled/cleaned/ and reinstalled it and the light went off for about 20 minutes of driving.

Then, the engine light came back on so i read the new codes and now it is misfiring on cylinders 1, 2 , and 4.

It has also not been able to hold a steady idle since before i redid the head gaskets and will stall consistently if my foot is not on the throttle. I am somewhat fed up with the car at this point and am not sure where to even start.

Any advice is greatly appreciated.

[Infosecdad]

Look for vacuum leaks and plugs not plugged in. Double check the timing before running much more.

[ALASKANSUBIE]

So i unplugged the battery for ten minutes or so and then re plugged it in and then turned the key on without turning the motor over for 15 seconds and when i started it to reset the computer and it can now hold idle without stalling, however, it is still very low hovering around 500 rpms.

[Infosecdad]

Drive it around for 20 min and see if it smooths out. Whenever you reset the ECU it takes a little bit to relearn idle. If it stalls more than a couple times, I would bet you have a lose vacuum line somewhere.

[MilesA]

Sounds like it could be a vacuum leak. It's very easy to dislodge something when messing about fixing something else. Pull the TMIC, check your vacuum lines under there, put some clamps on them so they stay put, check turbo inlet and connection between TMIC and the throttle body.