1999 Evinrude 15hp - stalls out

[suckerbrook]

I just inherited a beautiful '67 Starcraft with a 1999 4-cycle outboard. It starts and runs great at top speed, but when I back off on the throttle it runs for a short while then stalls out. I have to pump the primer bulb 2x to get it started again and then it only goes if put back to full (very challenging docking...) What could be wrong?

Any help would be very much appreciated!:

Thanks,
suckerbrook