Only thing i can think of is air in the system run the engine when its at normal temp see how hot the top of the rad is compared to the bottom of the rad If there is a big differance then bleed the system for air and feel your top hose if its soft you could have air in it. or double check if you have ac that the fan is coming in and not just the ac fan. Or switch the heater on hot air and feel how hot the air is coming out of the vents if its cold then it is air in the system. take it, Its not leaking coolent out of the exhurst or anywere else?