It is very difficult to determine your fault but would make sure your filters are clean and up to date, spark plugs in good nick,I don`t know but when motors are low on power you suggested it improved when you done your egr and you are hearing a raspy exhaust it may be the engine is struggling for air which could mean an air flow meter problem,I don`t know what sort of driving you do but have seen blocked cats give trouble also,a compression test could be worth a go also.I am not suggesting you go out and buy everything as it can cost a fortune but they are things worth looking at. Good luck.
cdc, March 2014