Error Code P1320

I was given a Error Code P1320.

Suddenly the some days ago I drove the car on a 160 km trip, after moving about 120 km the car started failing to accelerate (sometimes there was only a delay in acceleration) every time I want to pick up or overtake a vehicle ahead this happened mostly right after slowing down. This behavior repeated until I reached my destination. The following day the behavior was the same, I moved about 140 km before it started delay and/or even fail to accelerate.
when that happens the brake is stiff, the accelerator is dump.