First thing you would need to know is if the CFM ( Cubic Foot per Minute ) of the blower is more then the CFM that the engine can suck in without it.
If it can't push more air in then the engine can draw in on its own, with the pedal to the floor, then its just in the way and not helping.
Once you let off the gas, and close the throttle plates, its just blowing against them. If more air goes past the throttle, you will let off the pedal more, to find the happy opening for your speed.
All of the air fuel mixing happens after the throttle, so blowing air in isn't going to change that, unless your blowing it in at full throttle and overwhelming the controls.
Having bilge blowers in all of my boats, I don't think they have enough CFM to make a difference in an engine intake.
Try taking it out, clearing the possable intake restriction, and run it. You may see better performance.
Did a bit of research.
The blower in question can flow 235 CFM of air.
A 5.0 Ford V8, stock, throttle body can flow 500 CFM.
Your engine is much larger and needs lots of air.