EGR valve problem (p0400)

i drive prius gen3 2010 with 160K kilometers which behaved pretty good until recently.
From time to time the the car starts to rattle and shake and it feels like it is loosing power while driving.
Most of the times it happened no alert was registered in the car's computer.
I went to a repair shop and they said that they need to clean the EGR valve. The first time they did it it held for several months but then the problem returned. only one time i got the check engine alert and the error that was in the computer was p0400. I went to the repair ship and they cleaned again the EGR but the problem appears from time to time.
Any one had similar issue?