In the summer, I doubt your truck will run much cooler even if you take the thermostat out of the system completely. The only way to get it to run cooler is to get a bigger radiator.
Ethanol does make the engine run cooler and burn more fuel.
Regarding the ac kicking out going up hills-- I think what he means is the air blowing out of the vents cuts out. There are two vacuum check valves in the line coming off the manifold. Find that vacuum line and check for leaks. If you don't have a vacuum gauge, I'd just replace the vacuum hose and check valves (they're cheap). Make sure the vacuum line off the manifold isn't clogged with oil sludge.
Also, check if your plenum gasket is blown. Do you get a lot of valve clatter when the air cuts out?

 

If your plenum is blown, that probably isn't valve clatter, more likely is spark knock. Which is bad. Basically, what happens is the cylinder charge ignites before it is supposed to.... can have very bad consequences, ranging from bent rods, to holed pistons.......

 

I have owned and drove my 93' dakota with the 318 in it for several years now and two or three years ago I switched the 195 out for a 180. I have noticed that it doesnt run cooler, and there have been no fluctuations in the MPG. I get 15 mpg on average on that truck and have since the day that I bought it. I have tried several products that claim that increase power and mileage....The only time I have noticed a increase in power was when I gutted the cat and put on a glasspak. Still getting the same MPG. That said, I just did a plenum fix, new plugs, wires, cap and rotor, and magnaflow cat in my 98 ram. While I was in there I also put in the 180 thermostat in it. Yes, it runs better, and yes its getting better mpg, but I also do a lot of other work that would explain that as well.

 

I honestly cant understand how having a thermostat that opens 15 degrees sooner than the stock would change how the truck will run.

It was mentioned earlier that the function of the thermostat is just to open at a designated temp and then close again. It doesnt make your truck run cooler after it hits running temperatures as its already open and has no further function.

 

Because it cycles. The coolant isn't all a uniform temp. The stuff in the radiator is going to cool, while the stuff in the engine absorbs heat. Thermostat opens, coolant flows, until the cooler stuff gets to the thermo, then it closes again. Lather, rinse, repeat.

With the 180 degree thermostat, the engine will never get up to what the computer considers "operating temperature", unless you clue it in to what the 'new' operating temp is. (tuner) On the newer trucks, it actually sets a code. (failed thermostat) Because the computer thinks the engine isn't fully warmed up yet, it runs the mixture a bit leaner, because the engine is more efficient at the higher temp. Simply because it is programmed to run at that temp.

 

everything Iver been told in the past says the pcm will run rich until it passes the 160-170degree mark then it runs in normal at temp mode....even with my 180 stat my truck stays at close to 185-90 once fully warmed up...of course I do have the cai and headers and dual exhaust and terrible mpg so...(mpg was terrible with 195 stat too though)

 

I always thought headers would yield BETTER gas mileage?? No?? Must be that the nice sound the engine makes with headers, prompts the driver to have the engine make more sound....... A one pedal instrument.

I know after I put the exhaust on my Firebird, I never turned the radio on again.......

I don't know at what point the PCM decides the engine is "Warmed Up", I haven't gotten that far into it yet. I was a GM man for a lotta years though, and am intimately familiar with their systems......

For me, its just a matter of preference. The PCM is EXPECTING a 195 degree 'stat, and that's what the engineers had in mind when they were programming it, so, until I can tell the PCM otherwise, I will just stick with the stock unit.

Does the colder thermo help? Hurt? Neither? Both? No idea. But, I DO know that it was designed to run with the 195......

 

In the winter, in Michigan, your reasoning in sound. In most of the US in the summer, I doubt the thermostat cycles shut once it opens.
Also, I'd be really reluctant about running a newer engine at a cooler temperature than the engineers designed. With older engines it's not such a big deal because the wear has increased the clearances.

 

After the engine has been running a while, thus, getting ALL the coolant nice and toasty, there is a real possibility that the system reaches 'steady state' and the thermostat just stays partially open. Depends on outside temp..... on the REALLY hot days, yeah, I could see that, but, below about 80 or so, I would suspect that it does indeed cycle.

 

That makes sense about there being a cycle to the circulation of coolant. But, I am having a hard time reasoning that the pcm responds to 195 and only 195. 180 is a minor range difference and I am willing to bet that the pcm is designed to react to a range instead of an exact number. I say this cause 80 percent of vehicles are not maintained properly. And the pcm needs a fairly wide range to adjust for this.