I've been to total 4 different auto shops. Started with CAR X they replaced my radiator hoses after noticing the leak in the hose. $200 still overheated took it back they said coolant cap $14.50, problem consists I take to another mechanic shop which recommended a gasket tht was leaking coolant by water pump. Which was $200. Still overheated took it back to them and they found it leaking out the bottom of the radiator. Took the car to COMPARE AUTO which recommended radiator, water pump, tstat, $1100. Still overheated so they put a coolant temp sensor $90 still has the same problem with check in light coming on. It had about 3 sensor codes I believe camshaft sensor. I believe torque management code... and engine overheating code.
I don’t have any personal experience with these places you list, but based on the info you provided, they are all guilty of poor customer service and sloppy/incomplete automotive work IMHO...and a couple sound as though they might have outright shafted you, but that’s neither here nor there now, so I’ll drop it.
The last time I took it I believe they put some stop leak in it because the coolant reservoir has black slime and coolant dirty. The car doesn't leak coolant until it overheats but is still getting air in the system overtime. After getting my car from the shop it Usually takes about a 100 miles of driving before the system gets filled with air pockets large enough to overheat again. So air is sipping in the system somewhere...
Lots to unpack here:
1) no professional shop should have used the stop-leak on your car, especially on a hail-Mary like it sounds like. That stuff can cause issues in the cooling system elsewhere, like the heater core, etc. Nevertheless, it’s there now and should be kept in mind for all diagnosis steps going forward.
NOTE: if you can identify the brand/kind they used, that would be very useful in determining its potential for later issues. If you have the receipt from that service, check it for a part number or brand name.
2) the black slime was very possibly the result of mixing incompatible engine coolants during one of the prior services where they had to top off/fill the coolant. Either way, if it’s in that reservoir, it’s everywhere else too.
This is bad, very bad.
3) Not to be pedantic, but the air is getting into the system because the system is not properly sealed and allowed to build pressure as it requires. Is it leaking coolant? Maybe, maybe not. But there is a leak somewhere preventing the sealing up of the system, and that will cause problems 100% of the time.
Your underlying problem that causes the overheating could be one thing or a combination of several. If you want to fix it, you need to start at the bottom and identify the immediate cause for the overheat, then begin ruling out any/all things that can contribute to that.
Warning: The odds are that it won’t be easy or cheap to fix this overheat problem. You’ve already spent a lot of time and money with little to show for it. That’s unfortunate, but it’s in the past. More time, labor, and money is going to be needed for a resolution.
If this were my car, I’d start with identifying the root cause for the overheat. Low/no coolant circulation, loss of coolant, part failure, etc. Any or all could be the issue for the overheat. Find that out and then it can be addressed by further actions, more parts, selling the vehicle, etc.