The rad fan just cools the radiator, has little
to do with the thermostat, I run a 160* T-stat
and find the cold weather heat is a bit on the
cool side for defrosting but here in Cal there is
not much of a problem with the cold weather.

I would look to see what the temp of the T-stat
is, should be 180* , at least it was in my 89'  new
ones might be 190* or 195*

The symptoms you describe are consistent with
a stuck open or no T-stat installed, so you might
have got lucky, like me and got 2 bad T-stats in
a row, you can always boil water and watch the stat
open and close as you go from hot to warm water,
never heat a Stat with a torch, bad things can happen.

Wild

I would look to see what the temp of the T-stat
is, should be 180* , at least it was in my 89'  new
ones might be 190* or 195*

The symptoms you describe are consistent with
a stuck open or no T-stat installed, so you might
have got lucky, like me and got 2 bad T-stats in
a row, you can always boil water and watch the stat
open and close as you go from hot to warm water,
never heat a Stat with a torch, bad things can happen.

Wild

I agree with Wild.  Put the t-stat in water, put in a candy thermometor and see if it opens at the proper temp.  Should be stamped somewhere on the t-stat.

Also a soft/flat hose will cause an overheating problem not a cooling problem (unless it's the heater hoses going to the heater core).  And a stuck fan clutch will do nothing for cooling when your at highway speeds.  You'll just lose gas milage.

My best guess would be air in the heater core or some junk went into the heater core when it "boild over".  I'd pull off the upper heater core line and make sure that there is no air.  Then I'd try flushing out you cooling system.

When your all done, let your truck run in the drive way untill it gets to temp.  Then feel the hoses (upper, lower, heater).  If your upper and lower are hot but your heater hoses are cool, you might have a pluged core.

When you replaced the coolant if the mixture wasn't right, like putting to much anti-freeze, this would prevent the zuk from getting the temp. up.  this happened to me and all I did was drain some out and just add more distilled water and up jumped the temp into the normal range.

That's strange, pure water cools better than
Coolant/Water, it should of had the opposite affect

Wild

You guys rock in all the advice you're giving me!  I did notice one thing-  as advised in one of the earlier responses.

I started the kick from a dead cold engine with the radiator cap off, the water in the radiator started circulating immediatly.  I guess this is a bad thing that means the stat is stuck open, right?  Could it be- two bad stats in a row?  Would air in the system cause the stat to be stuck open?  

I did notice that bottom hose was a little flat and squishy- related? Or a whole new problem?  
I really haven't had much time to get on this, since I've been working out of my vehicle all day.  Fortunatly, I got my smartphone, which allows me to post on zukiworld.  U guys have been wayy more helpful than my mechanic.

... I started the kick from a dead cold engine with the radiator cap off, the water in the radiator started circulating immediatly.  I guess this is a bad thing that means the stat is stuck open, right?  Could it be- two bad stats in a row?  Would air in the system cause the stat to be stuck open?  

Let's boil this down (I know, bad pun ) to a few simple statements:

If a hose collapses, it will decrease coolant flow and make the engine run hot, not cold.

Pure water transfers heat better than a mixture of water and ethylene glycol or methylene glycol antifreeze. Running coolant mix with more than about 70% antifreeze will increase the boiling point but will actually RAISE the freezing point, not to mention causing hot spots in the head because it won't pick up heat the way water does. Pure ethylene glycol boils at about 300 degrees F and freezes at about 10 degrees F.

These numbers are off a Prestone jug: A 50/50 mix will give the best protection compromize for most climates (-34 deg F freeze, 265 deg F boil at 15 PSI). A 70/30 mix will freeze at -84 deg F and boil at 276 deg F at 15 PSI, but will not cool the engine as well. Warmer climates can use a 40/60 mix, which will freeze at about -5 to -10 deg F and cool the engine better. You need some antifreeze to lubricate the water pump, guard against boiling, and counteract corrosion.

New thermostats can be bad. There could also be a piece of debris under the valve, keeping it from sealing. It needs to be only a tiny bit off its seat to mess things up.

Because the ECU expects the engine to run at a certain temperature, I would suggest never using a cooler-than-stock thermostat at any time.

My Chilton manual shows the air bleed facing forward (toward the radiator).

If the thermostat is installed upside down, coolant flow can force the valve off its seat so you will get flow through the radiator when you don't want it - more flow at greater differential pressure as the water pump spins faster.

Also, a bad seal around the T-stat could
allow the coolant to flow around the T-stat,
and make you run cold

Wild