Sorry, long post

Details: 2011 Silverado 2500 LT, picked up in January, barely ran, found broken turbo, swapped good used unit in, works great, had a tuner set me up with a new tune as I knew nothing of how it was configured, ran good, just really noisy at 2000 - 2500 RPM during acceleration, lift accelerator and noise disappears, engine quiet mechanically beyond that condition, suspected tune/injection causing it. Also, once it got cold, had a consistent "Reduced engine power mode" almost every start. Didn't seem to limit anything, just the message. Heavy parts have been removed.

Last week, because I'm now quite happy with the rest of the truck's operation, decided to try a different tuner to write a tune, hoping to reduce that noise and eliminate the message. Provided the details, tune installed, drove for 2 days, yep, much quieter during that window and all was well.

3rd day, went to drive home from work, started it, "reduced engine power mode" displayed... oh well... drove for about a mile... hey, it actually is limiting the power. pulled into parking lot, shut it off, restarted, continued on my way, drove for nearly 90 ,minutes, no message, no issues.

One more detail, when cold outside (since early November here in MN), the front differential leaves a spot on the ground overnight.. yep, oil cooler seeps when cold. didn't lose a drop all summer. About every 10-14 days I get "low coolant level" message and add about a cup of coolant.

Set off for a 200 miles round trip this weekend, all was well so away we went, appx 80 miles into the trip, "Reduced engine power" message pops up, and yep, accelerator pedal doesn't do much. Surface roads for remainder of the trip.

Before the return trip, popped hood to look over a few things, hmm, coolant is low (just below the min mark, where the sensor usually trips the message) but didn't get a message. for last few days.. bet that could cause an issue, topped it off. Restarted, "REP" message returns. Shut off, disconnected both batteries for a few minutes, turned key on/off during no power cycle, reconnected power, restart, "REP" message returned.

Ironically, realized I had my scanner with, reduced engine power pid showing "ECT overtemp" and "Speed limiting" Temp gauge never went up to the 210 mark, usually rode just below it on this trip. Scanner reported 177-190 during the return trip.

So the question, hopefully someone has experience with this.

Will the coolant level sensor trip the ECT overtemp warning? Or is something else tripping it?

I see the level sensors are a known issue and part of the complete reservoir on these. I haven't had a moment yet to disassemble and test it.

And the Reduced engine power pid is toggling between ECT overtemp and Vehicle speed Limit Active. IS this one problem with the ECT issue and the speed limiting is a result of that action? Or do I have 2 separate issues?

Also, IN VCM Editor, I see one of the cells shown in the Comparison Log, is the ECT, Electronic Throttle Control, IN the stock file it is enabled, and in the Tuned File, is it is "Disabled" IS that part of the tune?