The P1445 is for your evaporative emissions system purge valve circuit. The purge valve sends fuel vapors produced by the gas in your tank into your intake to be burned (rather than venting to the atmosphere). If that valve is malfunctioning it will, at times, act like a vacuum leak - which is consistent with much of what you describe as symptoms.
If you want to verify, find out where the purge valve attaches to the intake (it is often on the throttle body). Temporarily remove the evap line and cap the intake port. If that clear it up then go ahead and sort out what the problem is with the purge valve. It might be the valve. It might be in the wiring. It might be in the system of vacuum lines for the evap system. Visual inspection is always the place to start.