1992 175XRI fuel issue

[mercuryxri]

1992 175XRI S/N OD165915
Issue: When idling below 1500 rpm either in or out of gear the engine will kill due to lack of fuel supply. I will have to pump the bulb many times to refill the fuel system and the engine will restart. If I idle or run above 1500 rpm the engine will run all day no issues. I removed the fuel sending unit to look into each of the two 14 gallon tanks and both are clean. I regularly siphon gas out of each tank by removing the engine fuel connector, use the bulb to establish the syphon flow and the fuel flows freely until the portable tank usually 5 gallons is full with no apparent flow issues. All fuel lines in the boat only have been recently replaced hence this should not be the problem. I am leaning towards replacing the pulse fuel pump. Am I going in the right direction, or should I look else where? Thanks in advance for any suggestions.

Follow-up: Apparently the last fuel pump rebuild was with non OEM kit. There were 2 sets of round diaphragms one rubber and the other a thin plastic. They were installed rubber as the sealing diaphragm and the thin plastic as a backing held in place by the expandable plastic pin. I think the diaphragms were too stiff to properly function at low speeds causing the fuel to be depleted.