I've got 150's the same vintage and never noticed anything like that. I have seen some weird stuff though.
These engines do depend on a good battery - I'm not sure I buy it 100% but people claim a weak battery will cause TPS faults and all sorts of things at runtime. Myself, because those 1000 mca batteries are quite a bit more $$ I only run something like an 800 mca and never had an issue, even when a battery is weak to the point where it can barely crank and needs to be replaced.
With that said there are some funny things that can happen due to smartcraft wiring - in my opinion it was not really well thought out from a "what if X/Y/Z happens" point of view.
#1 check your fuses - there are ways you can backfeed the trim circuit through other gauge wiring, so if a fuse is blown you might be robbing voltage indirectly from the ECU/injectors/pump or creating a huge draw.
#2 Optimax engines are notorious for chaffing wires - something about the amount of wires, type, critical nature of the wiring, and routing makes them really bad for this. It's not uncommon to decide to replace the entire wiring harness on an Optimax. Where I would be hunting is not as much the connections as much as for chaff and cuts/grounding/shorts - the trim circuit could be grounding or feeding some other electrical component.
#3 You might want to craft up a ***** of some sort and have someone try the switch on the engine itself to see if it makes a difference. If you see a different behavior with that switch then you know it's somehow related to the controls and not generally the trim.
Jon
