1996 5.7 Gi Bogging on throttle

I have a Volvo Penta 5.7 Gi engine (TBI) with duoprop outdrive.
Boat sat in drystack for some years before I bought, but has had some work done to get it running again. Boat is in excellent shape.
When in idle, will have an occasional stutter. Upon acceleration, engine will bog down and die but not every time. Usually after one maybe two restarts, it takes off like it's brand new. Also occasionally I am at about 3700rpm and can feel it's not at full power and suddenly will have full power again. Any suggestions would be appreciated.
Having said that here is a list of work/parts done so far:
-New water/fuel separator
-Drained all fuel and filled with new
-Oil/filter change
-New high and low pressure fuel pumps
-New Injectors (x2)
-Rebuilt float in reservoir and new seal
-Thorough cleaning on flame arrestor
-New cap and rotor
-New spark plugs

*Have run multiple tanks of fuel and changed fuel filter twice.

Motor serial number?
Have you measured fuel pressure?
Where did the new injectors come from?

alldodge said:

Motor serial number?
Have you measured fuel pressure?
Where did the new injectors come from?

Click to expand...

4110132061
Fuel pressure was measured by mechanic that installed.
Injectors cross referenced to matching auto injectors. (have taken off flame arrestor and verified good spray on both)

MEFI 1 ECM
EST ignition
VST and fuel pressure 29 +/- 2 psi

Sounds like insufficient fuel issue
Put a fuel pressure gauge on the port opposite the fuel line port and run it. Might have something getting clogged, collapsing fuel line, antisiphon valve need cleaning.

There might be a code but MEFI-1s were not that great

alldodge said:

MEFI 1 ECM
EST ignition
VST and fuel pressure 29 +/- 2 psi

Sounds like insufficient fuel issue
Put a fuel pressure gauge on the port opposite the fuel line port and run it. Might have something getting clogged, collapsing fuel line, antisiphon valve need cleaning.

There might be a code but MEFI-1s were not that great

Click to expand...

Thanks for the feedback! I'll run through it tomorrow and let you know my findings

MF96Cobalt said:

Thanks for the feedback! I'll run through it tomorrow and let you know my findings

Click to expand...

Also, where is the anti-siphon valve located?

If I may > what AD is suggesting it to measure the fuel pressure. You need to have a gauge like this one link. Do you have one? If not can possibly do a loaner from auto parts store. Only after validating there is an issue with pressure do you start to look for the reason why.

Perhaps I misunderstood your comment “I'll run through it tomorrow” followed by “where is the anti-siphon valve located?” as you were going to start to look at things like the hose, anti-siphon valve, etc. vs first check the pressure. If I am mistaken, I apologize.

The anti-siphon valve will be located on top of the fuel tank. It will look like this: