Windstar in trouble

Hello,
I have a 97 Windstar 3.8 and it has a reservoir leak I am wondering if this is a water pump situation because the radiator is full at all time antifreeze only leaks from the resevoir removed reservoir and it is not leaking from the container. If it is not the water pump is it possible for me to get some type of stop leak product that may help. Another thing with the same van is when I am driving down the highway my van sounds as if it is a large truck when I reach the speed of about 55. It sounds like bad tires then again it sounds like I am driving in the wrong gear. Automatic transmission changes gears fine from 1st to second but it seems like its not changing after I reach 55 or above. Transmission fluid is in there but it seems to be very thin for some reason I use MerconV but no luck . One other thing I would like to mention is my temperature indicator goes up to H almost and then the cooling fan comes on the van does not run hot but worries me. Someone please help.

Coolant leak.
Do you see coolant leaking externally? Or do you see no external leak, but constantly need to add fluid to the resevoir?

External leakage....try to track down the source.....can be tough.
Look at all your hoses and connections.....also look for signs of rust around the fittings at the water pump and the cross-over pipe that runs through the lower intake manifold.
Look for stains on or around the radiator....including the plastic side tanks....and where they connect to the alluminum fins.

Another thing to check is the hose that goes from the resevoir tank to the radiator fill neck (below the radiator cap).....a loose fit there can cause leakage, or the system to suck in air instead of coolant.
You might try replacing the radiator cap......but just get the regular cap at the correct pressure......no need for anything fancy here.
I found that mine kept failing to hold much pressure.......kept cleaning the seal seat...etc...only to have the problem return time and time again.......replacement of the cap solved the problem.

Internal leakage,
2 most common causes are lower intake manifold gaskets, I have a bunch of pictures of those in the pictures that the link in my signature takes you to.
Front cover, AKA timing cover, gasket. This is a MAJOR repair.
For internal leakage, I was successful with Bar's Brand of Stop Leak, for the timing cover gasket leak. Has held for a good 8 years and well over 100K miles.
The original pelleted type is the best, tough hard to add to the radiator due to the transmission cooler being right below the radiator cap.
While it did seem to slow the lower intake manifold gasket leak.....it did NOT solve the problem or last.......so I replaced the lower intake manifold gaskets.

I STILL have the factory original water pump on my '96 at over 216K miles.
The correct coolant types to use for your '97 would be traditional Green, which was used at the factory......lower silicate from the old style used years ago.
Green coolant is kind of hard to find, but you can still buy it.
I have G-05 in mine......which is a low silicate, long life coolant.
If mixed with traditional green, it is not a long life......becomes a 2 year product....but still is good.
G-05 is available under the Zerex brand as well as Motorcraft "Gold" brand.

If you get some air in the cooling system, it can make your temperature go high.

Another common failure is the dropping resistor for the radiator fan low speed operation.......
Easy to test at home.........Raise hood.......Turn A/C ON.......are the radiator fans ON.....and STAY ON? If not......most likely the dropping resistor is broken.......easy to repair.....I have a couple pictures posted that show the location of this part (a dealer part).
This will cause your coolant temperature to get higher before the radiator fans come on at HIGH speed.
The PCM turns the radiator fans ON at LOW speed when the coolant gets to a certain temperature.......if the temperature continues to go up......then at a higher temperature, the PCM turns the radiator fans on at HIGH speed.

"Sounds like a truck" and transmission shifting..... What are the RPMs at 55mph.
If they are high......your transmission is not shifting through all the gears.
My transmission had only 1st and 2nd gears as its failure........ended up replacing the whole transmission $$$$
If this is happening to yours.....the O/D light in the gear select lever should be blinking......indicating a transmission failure.
Also, make sure that the O/D button in the end of the gear select lever has NOT been pushed........The O/D light will be ON if the O/D (4th gear) has been disabled by pushing the O/D button......this should turn the O/D light ON.
It is normal for the O/D light to be on dimly with the dash lights.
Again, a FLASHING O/D light is an indication that there is something wrong with the transmission or a transmission control component.

Transmission fluid needs to be changed AT LEAST every 30K miles for normal service, using a Mercon V rated fluid as you mention.

I would like to thank you for your time and effort. When I was referring to a truck I meant one with really really big tires speeding down the interstate. When I make right turns it sounds as if something is scraaping like metal on metal I am thinking that it is my rotors but any suggestions.

I would like to say also that I appreciate the pictures and everything else that you have contributed..

Several things can cause the sound you mention.
Once, I bumped the thin splash guard that covers the back side (toward the motor) of the rotor......it would then rub slightly under just the right conditions.......solution was to bend it back out to its original positon.

Another thing could be the brake pads needing replaced........or a sticking caliper (I had my calipers replaced at around 183K miles due to sticking).
The way to tell if a caliper is sticking is that 1 of the pads will be worn MUCH more than the other......usually the inside pad.
So, remove the front tire.....inspect your brake pads.....BOTH of them.
Do the same on the other side.

Look to see if there is any sign of something rubbing.....tire rubbing a wheel sensor wire (they are held up out of the way by clips.....see if one of the clips came undone and let the wire drop).
Inspect the brake hose that goes from the caliper to the solid line on the body of the vehicle.
This inspection will also let you know if something has gotten stuck up in the wheel well.

Other possibilities....worn wheel bearing, lower ball joint, tie rod ends and sway bar links.
I have read a couple of posts of the swaybar actually breaking.....something else to look for.
Here is a link to a picture that shows front end components on my '96......your 97 should be pretty much the same.
http://rides.webshots.com/photo/2463787290011220610PMGWiC

Use a flashlight....and give your front springs a complete looking over.
One of mine broke WAY up at the top.
If you have a broken spring......and you plan to keep the vehicle for a while, I recommend that you get a pair of "quick struts" which include the spring, mountings, strut, top mount and bearing......all in one assembly.
If 1 spring is broken......you will need to replace BOTH front springs.