My 4-108 did the same thing.
Two good possibilities:
1. air getting into the fuel line
....could even be a tiny amount; or
2. fuel starvation
....clogged intake, defective diaphram in lift
pump, lots of other causes, ranging from very simple and cheap
to not-so-simple and expensive.
Mine turned out to be a pinhole in the copper fuel line from the tank. It ran thru the bilge
and was underneath
the fuel line, so not visible. Only found it by hearing a slight hiss when I used the lift pump manually. Ran my finger beneath the fuel line and, voila! A short length of fuel hose and a couple of good hose clamps solved that one.
Also, if you've recently changed your filters...primary or secondary...it could be that one isn't seated correctly.