CHUKKI

I ordered a radiator for my pickup from Rock Auto, that according to their website would fit. It also said it required a certain radiator cap- which I ordered. Well Nope! Radiator, altho' similar in size, when installed in the holes of the mounting bracket ,it resulted in the radiator sitting too high & so closing the hood was not possible. Also, the cap that Rock Auto said was needed for this radiator, was large; and this radiator requires one of the smaller ones, Then I purchased a radiator at Auto Zone. The also said it was the match for my truck. Took it back, since it was smaller. Next stop-Napa; they couldn't get one. So, they suggested, 1-800-Radiator (Nashville store). When I arrive, it's the same small one as Auto Zone. They said "perhaps the smaller one is more efficient."
So, smaller & thinner, I install it, as well as a new thermostat. I fill it w/ radiator fluid, start the truck, and turn on the heater to attempt the whole burping process.
It proceeds to start bubbling out, burping,...then goes empty. So I add some more fluid. Then, it's as if it threw it all up, and went empty again, and the engine started freaking out. I immediately cut the engine.
So....WTF? I've installed radiators before and am aware of the "burping" process.
ANY CLUE/ADVICE on whether OR NOT a 1988 Toyota 22RE (fuel injection) 4x4 pickup (manual transmission) works with this smaller/thinner radiator? The capacity is obviously less, the top plastic part is less, it is thinner. Does this indeed cause whatever it is that I experienced? OR, is there something else going on????
Frustrated, but not completely fed up! LOVE my Toyota! (480,000 miles and all!) (-;