Earlier this week I had my MIL come on. It was scanned at AutoZone and given the code P0128 which states that the thermostat isn't working right. Two weeks ago I had my coolant flushed and also had my mechanic install an 180 degree failsafe thermostat (I know that the stock is 192)because I was assured from someone at PFYC that the 180 wouldn't set a code. The day that the MIL first came on the temperature guage barely moved during my 20 minute drive to work. During the last couple days I noticed that the guage sometimes go up steady and sometimes stays low for like 10 minutes and then a few minutes later goes to normal driving temperature. Also the wierd thing is when I scan with the AutoTap the temperature it states is higher than the guage gives me. Is the thermostat really the problem or is it something else like the ECT sensor?

My temp guage never goes above 160degrees. I dont think the previous owner installed a new thermostat- but I could be wrong. Possibly my motor naturally runs cool? nooooooo can't be. its s/c'd. Maybe my guage is weird too. My SES light is on, but because of my lack of catalytic convertor.

New Tstats have been known to be faulty. If a new Tstat doesn't fix it then I'd look at the sensor.

Ahhh.... trouble shooting.....

First I would make sure there is no air in the system. This is most likely NOT the case, but something to look at.
Seeing how you changed the T-stat, it could be a faulty T-stat..... Also, you had the coolant flushed, this has been known to foul the low coolant sensor..... Worst case is you have a bad ECT sensor... I don't know what they cost, but the sensor is located right below the T-stat.
I would take the cheapest route first..... Pull the ECT sensor and clean it. If that doesn't work replace the T-stat, if that doesn't work replace the sensor.
It's possible that the ECT sensor being clean has nothing to do with the way it reads. If that's the case, I'm sure I will be corrected. I only bring this up because when the low coolant sensor gets dirty, it sends the wrong signal.

One thing I forgot to ask, is the ECT the only Engine temperature sensor there is?

There is a low coolant sensor in the radiator, but when it sends a signal it illuminates a "low coolant" light in your cluster.
This sensor is commonly fouled after a flush, but doesn't throw a code.