87 merc 150 xr2 Black Max need little help.

[Unkl L]

I just recently purchased a 87 hydra sport with 87 150 xr2 Black Max. Boat is real sluggish out the whole and will only run 5400 wot. It has a 23p prop. All cylinders have good compression. New stator was put on in March as I was told. Boat only runs 48mph and 5400 rpms. Everything I seen says should at least get 5800-6000 rpms easy. I plan to do timing and link and sync this Sunday. Also doing fuel pump and waterpump. I've seen post about deleting the idle stabilizer. is this permanent delete or just for timing purposes? Thanks everyone in advance.20190619_121537.jpg

[EuropeanAM]

If you would, please take a moment to review the Announcements at the top of the Forum, and be sure to provide the REQUIRED info with your posts. Thanks!

Idle Stabilizer: That's a PERMANENT delete. Just make sure you have the white w/black stripe wire that jumps from the inner to the outer switch box (bias circuit).

[Unkl L]

20190619_121537.jpg here is pic of serial number. Sorry about that

[Unkl L]

I did the link and sync adjusted timing got the throttle primary at 11° ATDC got max timing at 22° BTDC. Took the idle stabilizer completely off. It was three wires a red wire a black ground and a white/black. Only took wires off the first switch box. Did not take wires running from first switch box to switch box behind it. I rebuilt fuel pump. When I took it to lake it was hard to start. Once it started it didnt want to idle to well had it moments. I could now turn 6000 rpms but did not gain any mph. Still runs 48mph on GPS. It is still real sluggish out the hole. Have to ease on throttle and let it catch up and then I can lay into it. I did check timing Mark's with a dial caliper and got it exactly on .462. Any more ideas on what to do. I premix my gas. 90 Oct non ethanol 50:1.

[EuropeanAM]

Why is the Idle Timing at 11 AFTER? I would recommend trying 4 ATDC for Idle Timing.

[Unkl L]

That's what book recommendation was. I will move it the next time I puddle with it. Probably tomorrow afternoon. I was told afterwards the 0-6 atdc is best. So ur 4 atdc is probably spot on. Thanks