OK... So I get a call Saturday that this thing is overheating. Opened the air vent on the heater line and added almost a gallon of coolant. Problem fixed right? Wrong!! The guage goes all the way to hot and if you get any heat out of the vents, it's only out of the drivers' side of the car. Will not overheat AS FAST if you keep the rpms around 1500. Pulled the thermostat Saturday and it looked ok but replaced it anyway. Same problem. Pulled the water pump tonight and it appears to be in good shape. Putting new one in tomorrow anyway just in case. Turned air compressor down to about 15psi and blew air through all lines and nothing appears to be plugged anywhere. No coolant in oil and no smoke out exhaust. Also does not appear to be building pressure in the system above normal (not blowing coolant out of overflow). Can not see any obvious leaks in the system. Has anyone had this problem? Any suggestions on what it could be? My truck is down right now taking up garage space and I'd like to get this fixed so they can have their car back and I can stop working in the 10 - 20 degree weather. Thanks in advance for your replies!