Nissan Repair: 2001 Nissan Pathfinder, nissan pathfinder, timing chain

Question
I have a 2001 Nissan Pathfinder.  I took it to the dealer to have the timing chain worked on (tightened).  When they were putting the engine back together, they neglected to push a shaft in all the way and damaged the engine.  They replaced the top half of the engine with a rebuilt head, which looks different than the original that was in there.  Ever since I got the car back, it's been misfiring.  I've changed all the plugs and all the coil packs.  Right now, it's running fairly smoothly, but I'm still getting a DTC P1320 code.  Any ideas?  I've looked up other posts, and the usual answer is change the coils, but I've already done that.

Answer
Hi Judie -

I was working on a Pathfinder not too long ago, and had the same code. I changed what was called the swirl valve solenoid (located front part of the engine above the belts). and all was fine after that.

Hope this helps -
aloha
Calvin