Toyota Repair: 2005 Toyota Corolla 1zzfe, variable valve timing, home mechanic

Question
We have a check engine code P0012 (Camshaft Position timing over-retarded Bank 1.  What could be the cause of it?  It goes on and off and seems to be fixed temporarily by tightening the gas cap.  Is this the type of fix that a home mechanic can do??  Only once has the car kind of chugged and struggled off the line.  Could this code be related to the ECU recall on these vehicles (cracked mother board causing codes and poor shifting)?

Thanks

Answer
This is a trouble code for the variable valve timing controller (VVTi)toyota had issued a service bulletin for this, the camshaft gear that control s the valve timing should be replaced, it requires special tools and knowledge, the camshafts have to be removed to replace this gear.