97 dodge ram heater problem. Need help desperately.?

[Mike]

I have had my dodge ram for three years now and it has never had a working heater. I've taken it to every mechanic around and no one seems to be able to tell me what is wrong. I have replaced the heater core twice, the radiator, the water pump, the thermostat, and even had a burp valve put in the thermostat and still nothing. The temperature gauge in the truck says the engine is hot but i never have heat. However if i burp the radiator the truck will heat for a a while but never more than a day. I know on the second generation dodge rams the heater core sits higher than the radiator cap so i've had the truck up on ramps trying to burp the air out of the core because u can always hear a gurgling sound, but im not sure if I've got the truck lifted enough to get all the air out. Also the truck never builds pressure in the radiator u can take the cap off when the truck is warm and nothing. im just wondering if anyone has had this problem before cause i've gotten nothing from chrysler.