Merc EFI question

[jwclbi]

Hello, well heres the issue, the engine will run at low speed perfectly until I go over 2-3 thousand rpms or more and then slow down to low speed, say 800-1000 rpm. Then it will run for 2-3 minutes and stall. After that I hear a whistling sound from the efi. Is something suck open? My problem is I'm not familiar with EFI repairs and am kind of nervous to start disassembling it. i have the shop service manual but still kind of hesitant. Any thoughts?