Re: 150xr2 carb adjustment help
A lot of those V6 Mercs have six idle mixture adjustments. The thing to do is set all idle mix screws to initial setting (1-1/2 turns CCW from lightly seated) to get a fresh mix of fuel (for premix motors), remove the cowling, and warm the motor us and idle around while setting them.
Adjust all six, until you obtain the smoothest, fastest idle, but keep the RPMs down below 1000. Now try to accelerate. If she dies, start opening the top carb screws 1/8 turn and try again. if she still dies, open the mid carb screws 1/8 turn and try to accelerate. Finally open the bottom carb screws 1/8 turn, and retest acceleration. Repeat until you get reasonable idle and smooth acceleration. Take your time and be prepared to reverse adjustment if you make a mistake and lean/richen it too much.