I have not had any problems at all with mine. It has been flawless. I do not have a ton of hours on it yet. No problems with the alternator, starter or plugs. I have never used it to troll or much slow travel though either. It gets run at pretty high rpm’s most of the time. I really just use it to get to and from hunting spots and to run the river to fish. When fishing I just use it to get to the spot then one of the electrics take over. I have it set up to run xd-100 I have heard of some of the motors set up to run xd-50 have had some problems. However all they took to fix was to change the oil settings and go to the 100.
Sorry I am not of more help but knock on wood the etec I have has been strong and without problems thus far.