1998 mariner mag efi - Hard start/running when cold

[4winnsskipper]

Problem is the motor seems to have way too hard of a time getting started when cold. When i say cold, i mean the air temp is 35-40 degrees, water temp is 33-34, and the engine hasn't been run in days. I usually need to advance the throttle to 1/4 to 1/2 throttle for it to start, and usually it will start then die, then crank then burst to life, but if i don't keep the revs up around 1,500 to 2,500 (being careful not to exceed 2,500 per owner manual) or it will die again. I need to sit at the dock, and let the motor run on fast idle for about 5 minutes minimum, before i can throttle down to the normal idle of like 800 or so, then shift and go... but then the rest of the day, she'll restart like a brand new motor, as in, i just turn key, and it starts within a second or two and runs like a champ without any extra throttle etc...

so the other day it was 65 degrees out, and i wanted to see how it would start then, , with the motor ice cold, and not ran in a few days, it started right up, idled great, without any "extra" throttle needed...as a EFI engine should...

so basically cold air temp/water = very hard starting, running until engine reaches operating temp.

what should i check?

here's whats new in the last 4 months, non of which has helped.. New Fuel Filter, all new fuel line from tank nipple to fuel filter (inside motor), new quicksilver fuel primer bulb, and yes pointed in the right direction, new plugs, new plug wires (old ones clips that grip the spark plug were broken), all new fuel (drained and refilled with fresh gas), and i've been running quickleen through it...