Post Damper Plate Replacement

After replacing the damper plate on my 1983 PCM 351w, took her for a sea test and acceleration felt sluggish. Before we went out, and after using a feeler on the coupling we determined that alignment was ok, though I noticed the packing nut shimmy ever so slightly. I do plan on rechecking and adjusting any gaps in the coupler again, and my question is, if out of alignment even ever so slightly, can that affect performane of the prop?

Thank for your response, and I realize that my post sounded a little foolish, and it was; once I discovered tonight that the feeler I was using at the marina this weekend was not .003 or less, it was .010. That would of course indicate that there was an unacceptable gap around the coupler.

I do have a brass shim now, that I put a micrometer to and it is .003. I will try again this weekend. It is likely the alignment is out, because to replace the damper, we pulled back the shaft, removed the coupling, lifted the tranny and engine with a scissors jack, carefully blocked the engine with wood, removed the jack, removed the bell housing and tranny, replaced the damper, and reversed the process. That's a lot of pulling and pushing...

I would also like to add that before and after replacing the damper, I noticed that when rotating the prop shaft, the strut was "groaning" a bit, and it has never done that before, even when the boat has been out of the water for a while. Stops when I wet down the shaft log and when in water though. Therefore I plan to check the clearance carefully around the strut bearning, as well as the entry point into the boat (use a zip tie and check clearance around the shaft I believe I read). Another observation I had after damper installation was some dripping of the packing nut; usually it is very little, say 4-5 drips a minute if that. Now a steady drip. Could be because I backed the shaft through it a few times, but to me it might also indicate that I am out of alignment. ?

While I am planning on trying again and adjusting things this weekend, I wanted again to confirm that this is likely the cause of the sluggishness I felt when starting to accelerate through the water. ? Perhaps it really doesn't take much mis-alignment. Thanks again for your insight.

I had watched the video, and will do so again, thank you.