Hello, recently my b6 1.9tdi 2001 96kW ESP light came on and glow-plug light started flashing. The rpm stays at ~1100 and it dosen't accept any throttle. The problem dissapears after restarting the car, but repeats after some time. What could be the problem?

I've read some forums that stated that there could be drainage holes blocked, but they all seem to be clear. Break lights work as well.