thought i would update where i have got to,

Changed both raw water pumps for Hardin gen 7 ones, and the water presure sensor. One engine is running the smoothest i have ever heard. the other one, is still playing up.

It makes a cyclic sucking sound at cold idle. then sometimes stalls. I ve checked the earths, and about to run it from a small tank to see if its a fuel issue. Any other hints, no codes are coming up any more.

so far, i have changed,
raw water pumps
fuel filters (both disk and catridge)
oil filters,
oil,
coolant
belt
Idle control
Fuel injector cleaner
water presure

anywhere else but to check the fuel?

Did U swap ECU's

didnt get that far, i had unpluged it ready to swap, and thought i would just replug and give it a go.