Traction Control and Stabiltrak issues

[Prof_h]

Hi Everyone,
Vehicle details: 2010 Tahoe LT, 5.3L 8cyl, 2wd
I've been dealing with issues for a while and don't really know what to do next. Hoping someone here can help out, maybe have a new suggestion.

Problems:
These issues are happening at random times, with cruise control on or off.

1. I can be driving at 75mph and the truck speedometer starts bouncing all over the place, same with the tachometer. Service Stabiltrak and Service Traction Control flash and my speed drops. This has happened when driving for 1hr at a set speed, or after driving several hours at the set speed. It just happened for the first time when I was backing up at a boat dock.
Most of the time I can pull off the road, turn off the truck, wait a minute, then start and be on my way. No codes and things are fine till the next time it happens. Sometimes I cannot get low gears to work, or the manual low gears to work, limp mode. I can't always pull off and turn off the vehicle, so slowing down is a real problem as I can't speed up very quickly without low gears. I'm in FL so most of the time I can get up to speed on flat roads. It doesn't feel like the throttle is working.
Sometimes I get the engine light that comes on and U0101 coder is present on my OBD reader. I also get NA fault code, which I just think is something my OBD reader is too old to get the code.

2. I have also noticed that on occasion when I am slowing down to stop at a stop sign, I hear a clunk and it feels like someone hit the back of my truck.
This has happened about three times in the last year.

I've taken the vehicle to the Dealer with the service engine light on and I've given them the codes that I've noted, more than in this post as I can't remember all of them. Had my transmission flushed, filter and fluid replaced, Also had the radiator and water pump replaced. They said the only problem was the radiator was leaking into the trans. fluid. Dealer said my transmission was fine and no codes were present.

This all seemed to start after I had air shocks put on my truck and the mechanic disconnected my ABS sensor to my left rear wheel. That mechanic said I'd have to replace the sensor, it was bad. I plugged it in and the ABS light went out, but all this Stabiltrak/Traction control stuff keeps happening.
Please help if you can.

[j cAT]

you have to provide all vehicle details and the codes . year/model/drivetrain/engine/mileage/any mods like lifts .. you say air bags installed also dealership work done that helps. random power loss can be the fuel pump so post what the fuel pressures are.

If this is a 1998 type truck the ignition switch is a good guess.