Mercruiser Stalling

[oldfielder]

1999 Mercruiser 5.7, 250hp, carbed, 350, stalling after running for about a minute. Surges a little and then stalls. Starts every time and then stalls. If I try to throttle it, stalls. I'm intrigued because it does the same thing every time. It has an electric choke. Electric fuel pump. The carb was rebuilt last year. What should I check first? Would a clogged fuel pickup in the tank continue to allow me to start the motor? Does it sound like the choke is malfunctioning? Can't get anyone to look at it for a week so I thought I'd see if I can chase anything down.
Thanks