doesnt overheat but temperature fluctuates radically

[wiswind]

I have run across the issue with burping air with my Chrysler products that I used to have.....
When you don't have a spot to bleed air out at a high spot on the motor......this is a common issue.
I would be pretty certain that the need to burp the air out was a issue for your situation if you fully drained the radiator.
I would spend a lot of time rinsing out your cooling system to get all the chemical out......so that you don't have it in there to compete with the additive package in the coolant that you are putting in there.
DON'T leave just water in there overnight if it is cold in your area (I'm in Wisconsin.....and it has been COLD lately).
Use steam distilled water at the end of the flushing routine to have in there for when you add the coolant.....you will NOT be able to drain all the water out......maybe 1/2 of what is in there (6 quarts or so).
Then follow the steps that I listed above to burp the air out.......I have had to do it a few times to get it all out.
After that.....you may need to add some coolant to the overflow bottle 1 or 2 times.
Of course, after that.....if you need to add coolant.....even a quart or so every month.....you will need to address that as a coolant consumption/ leakage issue.

Let me add to this...that I ran a LOT of the Bar's brand of Stop Leak......I had the silver stuff......and I did NOT have any sludge.....when I removed my upper intake manifold......the water passeges were very clean.
The stop leak was like particles....not goo......in the coolant.
When I flushed it out and put in new coolant....I had the old coolant in my old distilled water jugs....and you could see that the stop leak was particles mainly floating on the top......or suspended in the coolant.
If it were me.....I would add some of the stop leak product.......as preventative maintenance......
If you develop a slight seepage (the early stages of a real leak) the stop leak will help to seal it up.
It has, so far, taken care of my front cover gasket leak that developed over 5 years ago.

[deathstar96]

no the original problem of heat fluxuation and the problem of the interior heater surging from hot to cold to hot again was NOT from me draining the radiator, it just starting doing it one morning on its own without me touching anything, I didnt drain the radiator until after the problem had started. diagnosis is 9/10 of the law, its easier to fix a problem than to diagnos a problem...LOL I will be glad when this is behind me, I will be glad when I have a second vehicle so I dont have to rely on a Ford...LOL

I have two classic 65 mustangs, a convertible and a fastback that are in restoration process but they wont be available for sometime and I need this deathstar to live at least one more year....LOL

I will say I like the comfort and the handling and the versatility of the windstar but my GOD the trannys and the head gasket issues and intake gasket issues are terrible!
thanks for all your valuable time MR. wiswind.... and the rest of the gang