15 hp merc dies when throttled

[<BubbatheLoveSponge>]

One more try here. 2 engines, both 1999 15 hp mercury 2 stroke tiller handles, 1 is manual start, 1 is electric. rebuilt carbs on both of them as they were leaking. with help from some of you I was able to get the float adjusted correctly, and they both start perfectly and idle great. they both run fine in gear at idle speed, but both will die when I give them gas. this topic has posted before and I tried richening the mix as has previously been suggested--no luck. they will run at full throttle if the choke is used at just the right time when giving them gas. Once they are at full throttle the choke is not necessary to keep them running. however, reducing the throttle with the choke pushed in will stall them. I'm sure this is something I've done to them as I did the same maintenance to both and they now have the same problem.
Thoughts?

[<Sqaltwaterboater>]

Basically what you're doing by pulling the choke knob out at the right time is you're acting as a manual accelerator pump, shooting an extra dose of fuel. That should be correctable by opening the idle mixture screws 1/4 to 1/2 turn, but apparently that isn't the case. I really can't think of anything regarding rebuilding them that would cause this unless they aren't quite clean enough...but both? I'm drawing blanks here. How far out are the idle mixture screws now?