2000 4.7L V8 Overheating...again

I drive a 2000 Dodge Dakota Sport w/ 4.7L V8 engine. I have been dealing with an overheating problem for about 6 months now and have nearly exhausted all hope of correcting the issue. It has been in the shop on 4 separate occasions and seen 2 different mechanics. The radiator has been replaced, the thermostat and thermostat housing have been replaced, the radiator fan works properly, hoses have been replaced and no subsequent leak has been found by either mechanic, they haven't mentioned the possibility of a blown Head Gasket (nor has the typical "milky residue," shown up in my oil cap). Each time I got it back from the shop the problem was fixed for about two weeks, then returned and slowly got worse. It overheats in idle (with the fan running), on the highway at high speeds, and while driving slow. Sometimes it only gets about 3/4th to the red (usually when its cool at night) and sometimes it will hover just below the red; while I'm doing everything I can to keep it from hitting red (defrost on, revving engine). Some days it takes a little while to get hot and some days it happens very quickly. I'm tired of sinking money into the vehicle but as a recent grad I don't have the money for a new truck at this point. Was referred to these forums from a sports board I post on..suggestions from them included heater core clogged, water pump gone bad, fan clutch. Any ideas and suggestions are appreciated.

I had the same problem with my truck. replaced thermestat, cap, fan clutch. flushed out sytem but it wouldnt solve the problem. What the problem was, was the water pump. I never even bothered with it cuz it didnt leak out the blow hole. so i figured it was good. but when i took it off i could see that it wasnt working right. the water damage from it not working was pretty bad. but once i replaced it, it stopped over heating. the most it gets to is about 212 which is a bit past half way. and to replace it is very easy i wouldnt take it to a mechanic save the money