Stalling problem

[02z71Hoe]

So last winter i was having a problem to where my 02 tahoe with the flex fuel 5.3 would stall but would always start right back up. Replaced the fuel pump, iac valve, cleaned the throttle body 4 time, new fuel filter, pcv valve, sea foamed the engine twice, new coolant thermostat and a ton more of stuff. Well it went away for probably about 6 or 7 months and now its back. I dont know what else to replace. The crazy thing is when its about to stall the temp guage drops all the way to zero and then goes back up but by then the engine has already stalled. I also have low idle like around 450 / 500rpms. The thermostat was the last thing i replaced before the stalling went away. Another thing is i can wiggle the thermostat where it plugs into the engine block before i go anywhere and it wont stall during the period im driving it. How could i check for frayed wires or a lose connection.. any help would be greatly appreciated!