I do not own an E-Tec, but I am a fan of “Direct Injection”!
Here is a story that happened to me, and a lot of the parts of your story sound like mine.
I had a “98” Opti 150 that after about the third time out, had the same symptoms as you state. Only thing, is that I could at least idle in gear. After idling for about 20 minutes, I could finally give it some throttle, and it would run. But, even at half to full open, the motor would shut off for an instant, and then come back on. This would really shake up the transom.
Chappy will probably chime in here and tell of the “lost trolling motor”! But I digress.
Since the thing was still under warrenty, I took it in.
What I found out, was that a wire had come off of the oxygen/temp sensor. It was my fault! I was showing off the motor in my garage, and since this was the saltwater version, it stands taller that me! So when I was putting the cowl back on, I caught the wire and it pulled off. The dealer found this, and I haven’t had a lick of trouble since. I sold that boat to a friend’s buddy, and it has not given him any trouble to date! I bought a “02” Opti 150, and it too has been flawlwss. I am more careful, (I get some help!), when I remove and install the cowl.
So, like most others said before me, give the dealer a chance to check it out. Hopefully, it will be something stupid, like my problem! I feel you will be happier in the long run with the 2 stroke. I think that all of the makes of “Direct Injected” motors are the cats meow! 2 stroke performance and 4 stroke economy! Best of both worlds.
But like you also stated, the electronics on all of these motors is unreal! I can fix anything, if I can put a wrench on it, or hit it with a hammer! Electrons, and 4-20 miliamps, scare me!