I am having trouble figuring out what is wrong with my aztek. Flushed out the coolant and days later started over heating and leaking. Took it to the garage and they said it was the intake gaskets. So I got that fixed drove it down the road a couple miles and it started over heating again but not leaking any fluids. Took it back to the garage and they said they THINK it could be the head gaskets. I took it back home and had some people look at it and replaced the water pump and thermastat. drove about 15 min then started to overheat again. No one else seems to think it is the head gasket as there is no signs over antifreeze in the oil, or burning of antifreeze out the tail pipe. It wil run forever idelling without overheating but when I drive it down the road after about 15min of the gauges going up and down it overheats and the coolant is backed up into overflow. I can bleed the air out of the lines and run it for another 10-15 min then have the same thing happen. Does anybody have any ideas?