Weird cooling on my 84 D150

So 84 D150 with 360, my DD. Drove home last night..approx. 5 hours, truck would barely warm up at times. Sometimes temp guage would be 1/2 way, sometimes 1/4. In the past few weeks, at times it would overheat while idling OR after a restart. For example I drive to gas station, fuel up and then turn key fwd and the gauge is pegged to the top AND when I start it steams from under the hood. Coolant protection is about -25*C, I know its not near enough, and Im strengthening it today.

About a month ago the lower rad hose blew off the rad. I pulled over and was able to get the hose back on and the rad topped up with water(all I had and about 10 at night). Truck kept overheating HUGE the 5 miles home. I had to stop about 3 times. Next day I replaced the lower rad hose and added coolant. Maybe not quite enough, approx. -20*C protection. I also bought a t-stat, but didn't replace it for a bit. Both prior to and after changing t-stat the symptoms are the same.
So new t-stat, new coolant to approx. -25*C, and new lower rad hose. Rad looks fairly new and the previous owner told me it was new, so Im guessing maybe 3 years old at most??
Any ideas??

Thanks all