I've been extremely busy. I've called the shop that did the install and talked to them about the zero point calibration. I've lifted many trucks and never heard of this or had any issues like this. Also, the lights went off about 30 mins and haven't returned. But still having the TC activate on turns and driving me nuts.
"Zero Point Calibration of the Yaw Rate Sensor" is the technical terminology. When you lift the vehicle you change the ZPC or the "Zero" of the vehicle's Yaw Rate Sensor (it's a sensor that detects the difference between the vehicle's momentum and the direction it's traveling and I believe to a degree it detects roll as well). When you lift the vehicle, disconnect the battery for an extended period of time and/or affect the memory of the ABS system (i.e. new ABS module, sensors, ect.) the system needs to relearn "Zero" so that it's relative measurement of Yaw Rate is accurate.
This is done via a ZPC of the Yaw Rate Sensor and provides the vehicle with a Zero relative to it's current configuration. This allows the vehicle to better track and predict the vehicle's momentum and direction when driving, an out of calibration Yaw Rate Sensor can lead to erroneous readings and thus more sensitive or incorrect VSC/TRAC activation.
As I said earlier though, I do suspect that the Yaw Rate Sensor also tracks Roll as a measurement (I could be wrong on that, it's been a bit since I delved into detail on those components). Which means that while performing a ZPC will help somewhat it may not alleviate your issues completely. The reason being that your center of gravity is higher and thus the Yaw Rate sensor itself is higher meaning that forces will be exaggerated on your lifted vehicle (i.e. your now taller vehicle with a different spring rate, and so on will roll more in a turn than a stock vehicle) and thus the VSC/TRAC system may think it's in danger of slipping when it's not an prematurely activate. There's nothing you can do about that specific side-effect, for the most part adjusting your driving style helps to mitigate that, or just disabling the entire ABS system does as well.
This isn't new to Toyota Trucks/SUVs, nor to newer Trucks/SUVs in general; so if the shop you talked to hasn't heard of it, it's probably because they haven't bothered to be knowledgeable on anything made in the last 20yrs.
Post Note-
You also didn't mention how aggressively you're driving the vehicle when VSC/TRAC is kicking in. I can get VSC/TRAC to be a bit annoying if I start throwing my 4th gen around with it's heavy 35's, I also could get it to happen with a sharp enough turn when I had 33's and maybe even stock tires. Also if you have 34x10.5 tires then they should be nominal 34" diameter give or take a 1/8" of an inch, unless you're using a metric size (your comment about them being closer to 33's seemed off since you gave a floatation size that should be fairly consistent, you only really get that "almost a 34 inch tire" measurement when you're converting metric to floatation).
The Stage 2 kit is a 2.0" diameter shock front and rear and if I recall they are running 600, maybe 650lbs springs on those front coils (I forget so anyone who runs Icon stuff please correct me if I am wrong), that combined with the heavy unsprung weight of 34's and mildly aggressive turns could be enough to contribute to VSC/TRAC kicking in a bit weirdly. There's also things like your wheel size/offset (i.e. if you're running too slim or too wider wheel and what the offset is), alignment specifications, and how the Icon kit affects your SAI (Steering Angle Inclination) which could all contribute to your issue.
Bottom line; lots of variables and "maybes, ifs, possibilities" to go through. Start with a base line first and make sure that the ABS/VSC/TRAC system is calibrated correctly to your current vehicle set-up by doing a ZPC then we can work from there.
Also you said the "Service Engine" warning lamp was on? Do you mean the MIL (Malfunction Indicator Lamp, also known as a "Check Engine Light") was on? If so that's more than likely not related to your ABS/VSC/TRAC system.
