been fighting this for 2 weeks since we go tht boat in the water, 99 502 MPI's w/Cool Fuel. motor runs fine out of gear, breaks up by 2k under load. so far it has new - plugs, wires, cap, rotor, in the ignition. put a gauge on it, has 31 lbs at idle, 34 lbs on the spring (vacuum line disconnected). fuel pressure stays steady even under break up. the other motor, has 39 ish at idle and 42-43 on the spring. so this weekend we put a new fuel pump, andit has perfect lines, same results, so it's not a flow issue. I'm guessing that the factory regulator isn't adjustable, so do I throw a new 860349A1 Fuel Pressure Regulator on it next? next is what are the chances my distributer module runs perfect til almost 2k?

Check and see if the drive lube reservoir has lube AND that the sensor isn't stuck. This will usually trigger an alarm and a safe mode where it breaks up like you say around 2000 rpm. If you don't get an alarm make sure the alarm actually works (i.e. makes alarm noise).

Is that fuel pressure when running in water or when running on a hose, big difference as to the volume it needs

Would need a serial number to determine regulator
0L017000 THRU 0L085432 = 860349A1 Cool Fuel Gen 1 Mallory 9-33207

0L085433 THRU 0M024999 = 861126A1 Cool Fuel Gen 2 (43 psi) Mallory 9-33206

UPDATE, replaced the regulator and now both motors have the same fuel pressure, all this has been done on the water. i also swapped out the distributer module. same results, breaks up same as before consonantly before 2k. so i'm going after a scan tool in the morning and starting looking at that end.

This is what I think i'm going to start looking for, we actually pulled the bottles and washed them out with brake clean this spring. but after all we have changed it has been brought up that it sounds like the ECU is in Safe Mode. What else can cause a motor to go in to Safe Mode?

You should be able to bypass any of the alarms, and especially the drive lube one easily. Just unplug the wires and make sure they don't touch a ground.
I had a wire splice come apart for drive lube alarm and one end was hitting the intake. It was setting off the alarm, but no power reduction.

Was the cause found? What was the fix? I am having a similar issue.