No mid range throttle control on 200 hpdi.

Motor idles perfect and runs great up to 3200 rpms. Motor will not hold steady rpms from 3200 to 4200. Engine increases rpm without moving throttle forward. From 4200 up I again have normal throttle control. Has identicle issue coming down on rpms. No control from 4200 to 3200.. If I play with the throttle and get it to hold a steady rpm between 3200 and 4200 the motor seems to run rough.
Any help will be much appreciated!
Thank you,
Nick

[boats.net]

If it's a model with O2 sensor it may need to be cleaned.

ck tps sweep in mid range

[smalldog]

Change your high pressure fuel filter. Sounds like the high pressure pump is starving... Just a thought.