Sounds like a boat specific problem. We have 2026 25 lsv and have had no issues with the depth finder. Can’t imagine there is a big difference between those two models. If you haven’t had your 10 hour break in surface yet, have the dealer take a look. Also if depth is a concern at 2Omph it might already be too late. 

I don't want to de-rail. Can we confirm the how to on an '02 IAC re-set? I also replaced mine, but didn't know there was a re-set procedure.

Thanks in advance.

Summit Racing or other aftermarket high performance vendors offer harmonic dampers for Small Block Chevrolet engines:

https://www.summitracing.com/search/department/engines-components/part-type/harmonic-balancers/make/chevrolet/engine-size/6-3l-383/engine-family/chevy-small-block-gen-i?autoview=productname&cm_mmc=ppc-google-_-search-_-general-terms-_-keyword&gclid=cjwkcajwgo7rbhbkeiwaznp85ucq2oqtnct1s-rntqf9_jkns2tz80vyghmnlafhdftphu-u2uiydhoc1puqavd_bwe&gridpagesize=16&sortby=default&sortorder=ascending

Note: to go this route you will need to confirm that it is externally balanced which is a question for Indmar or @csleaver. 

I upgraded from a 2015 Axis T23 to a 2026 Malibu 26 LSV this year and I'm incredibly disappointed with the depth finder on the new boat. It mostly works at surf speed, but is pretty much worthless at 20+ mph. The old one wasn't quite as good at speed as at idle, but this one is dramatically worse. My friends with Mastercrafts, Nautiques, and Centurions all have depth finders that work at cruise speed and it's a pretty important feature given how and where I mostly use the boat due to dramatically changing water levels month to month. 

Are my expectations too high? Is it a boat problem (i.e. just me) or a model problem (all 26 LSV owners)? 

Does it run with the engine hatch open??  I only ask because I had a leak in my silent rider muffler and it was pumping exhaust into the engine bay.  It would sometimes cut out at idle.  When in motion the exhaust was being drawn out, so it would run.