Need some help with 2004 125hp 2+2 motor

[JUSTIN TANK]

i have 2004 mercury 125 hp outboard replaced the accelerator pump,fuel filter,fuel bulb and line,new plugs,rebuilt the carbs did a compression test,marked the prop to see for a spun prop still having issues trying to get up to speed at 1800 rpms you can feel the motor shake and run rough only at the 1800 rpm rang other runs like a dream any ideas last thing I can think of is the fuel pump took that apart today everything seemed fine one of the rubber gaskets seemed stiff but not sure if that would affect performance penny for your thoughts much appreciated thank you for your time!!!