Good News !
Today I drain all the coolant , release the two heater core hoses and flush all out . I did a flush for all the cooling system too.
I filled a coolant and drain all the air out.

Now...
Driver side - 131 F
Passenger - 122 F
Before...
Driver side - 92 F
Passenger - 80.4 F

I follow after the steps that describe in this video :

Nice to hear you fixed the issue, thanks for sharing what you did to fix the issue!

I think I was happy too early ...
Today I felt , passanger side , cool air again :(
I measure the temperature (after long driving) :
Driver side - 120 F
Passenger - 104 F
I cheaked the coolant level and it'* Ok .
what could be the reason for this difference ? maybe the heater core leaking and air going inside?
for replacing the heater core , I need to remove all the dash or I can do it like I did in the Lesabre ? anyone have a guide to do this ?

Please help me I desperate ...

After the flush did you run the car for a while with the rad cap off?
Are you checking the coolant level in the morning when cold, by removing the rad cap to inspect the level?
Add to the rad if it'* down, can take a few days to get the air out, & driving it for longer trips.
I also ensured that the engine temps a few times each day, had climbed well above the 195 degree thermostat opening temps, by having it idle longer.
Took me 3 days after the system was opened, refilling rad each morning.
Run it with heat on hot.
If you think you have any leaks anywhere, have it pressure tested.

Yes , I runing the engine 10-15 minutes after it reach a operation temperature and I filled coolant too . all the air was drain by opening the thermostat housing nipple.
after a day and long driving I cheaked the coolant level again and it'* seem ok .
I didn't cheaked the level with pressure test , and I didn't saw a wet carpet or sign of leaking .

can be other reasons for the temperature changes after only one day ?

I cannot think of any changes that could cause the temp to change so much in one day, unless it got a lot colder outside, and or the coolant to water dilution rate changed, maybe that is what happened, the water and coolant mixed up better after running through there a few times.
It may be something else like a little air still trapped in the system, but if you say you released it from that nipple on the thermostat housing, then there should not be any air left in it.
Do you know if the thermostat is a 195F, or did you ever put a lower temp one in, like a 180F?

Is it not performing enough to keep you warm when it is cold out?

I don't know which thermostat insalled . if I put in a lower thermostat it will help ?
when the car reach to the operation temperature it stay there , even when I drive on highway .

In the winter a 195 would be best. For summer, a 180 assists in keeping the system a bit cooler.
I used a 195F Delco thermostat and also drilled a small hole in the 12 o-clock position, to allow air to bleed out easier. (Thanks to William!)

If your system is not pressurizing properly, it will not get all that hot.
A leak or the water pump could be the issue as well. If there was a huge difference between driver & passenger side, I would think it may be a blend door actuator.
I would recommend a pressure test be done.
One day I also found a small leak at the rad cap, a new Delco solved that problem!

Thanks Soft Ride , I will try this ...

I'm not sure how much a local shop would charge you for a pressure test, but if it is over 50.00 I'd consider buying the tool to be able to test it yourself, I never see tools as a bad investment.

http://www.amazon.com/Mityvac-MV4560...0070068&sr=8-1

I'm thinking your actuator doors may be out of calibration, you can try to rehome them, there are a few ways, one involves a Tech II Scanner, the other a special menu via the control head, the other, the one that I think will work for you is the following.

With the car shut off locate the HVAC fuse under the hood, remove it and wait one minute, replace it and then start the car, allow HVAC to perform self-calibration, do not do anything to interrupt it, after it is done verify there are no DTC codes set.