colouny

Hi i have a small problem,
My V6 30v 2.8 ('99year made) liter engine starts to misfire or something similar ( it feels like some of the cylinders doesnt work) between 900 and 1800 RPM, before and past that range is like calm water, no power loss or anything silimar.

Wel have to be honest, i have already spent a lot of money trying to repair this anoying thing. It almost have my taken my hands down, but still in the mood to fix this.
I have already replaced everything what is related to spark: HT coils, Cables, spark plugs. replaced also TB ( already resynced), all of oxygen sensors, carried out compresion test( all cylinders have the same readings).

The car doesnt give any error codes.

Could this be causer by leaking EGR valves?

Please pint me on something. Thanks.

By the way, Happy new year everyone...