I think there's a mixed bag on that advice: The old Innovate LC-1 (and maybe LC-2?) had separate ground wires for the power/heater circuit, vs the sensor circuit. So you'd want to share sensor ground with the MS so they'd have a common reference point (14.7 on the gauge should come close to 14.7 reading on the MS). With the MTX-L, Innovate combined the ground for the heater and sensor circuits, so it becomes noisy/unaligned from what the ecu reads even if they share a common ground. All the reports I've read, people had to manually adjust their wideband calibration table in TunerStudio to get them to line up even with the shared ground point.

Maybe having the power and ground shared with the ecu is drawing too much current away for the wideband heater/gauge, and causing the weird symptoms you're seeing (100% speculation here). Can you re-wire it to draw from somewhere else temporarily, and see if that clears up some of the trouble you're having? The only downside is not aligning 100% with the ecu, which is happening already with the shared power source setup currently.

I redid the ground, I soldered back the ecu ground wire, and used a ring terminal on a good ground location separately for the gauge. I'll attempt to rewire power from another place. Do you have any suggestions on where I should get power from?

I'm usually super lazy with mine, and just tap into the cigarette lighter +12v at the bottom of the dash column. It's easy to snake a wire down behind the dash from where I mount my gauges, and it's switched with the ignition. Probably not the cleanest power source, but it's worked for me.

My car has a push button start that came installed when I bought it. Behind the cig lighter is an older aftermarket fuse box used to hook up a stereo system, thats where the push button start wires go, and then that box is wired into the factory harness that also runs to my ignition switch. The wire for my ignition switch is cut out, as the push button is wired directly into that spot. It's confusing lol, Is there perhaps another wire to use?

Are any of the outputs of the fuse box turned on with the ignition switch set to "on"? If not, you can steal power from the switched wire on the radio harness. I'm not sure what color it is, you'll have to play around with a multimeter to see which one is switched +12v since it varies based on year/stereo type.