Help with strange Chevy problem

[trect]

A friend asked me to change his water pump and thermostat on a 99 venture, his complaint was overheating and a whine coming from the waterpump. I changed the water pump no problem the thermostat on the other hand as you know was fun. I went with the throttle body method instead of the crossover put in the new thermostat and it started right up however after running a few minutes it started getting hot like in the red hot. I can hear a hiss when the vehicle is turned off it is somewhere by the throttle body/thermostat area. i was getting white smoke out of the exhaust and in the air intake so i took of the throttle body again and replaced the thermostat again I put a new gasket on the throttle body again and it started right up again. However there is no heat blowing from heater and it is still overheating and there is still white smoke. There is also a check engine light the light was flashing but no longer comes on. the car either starts right up or stumbles through a few cranks and sputters. So what am i looking for? I was considering the Coolant Temp Sensor, Throttle Body Gasket, and the dreaded Intake Gasket.

Please help!

Tony

[phipps]

The flashing check engine light indicates a misfire.

Did you bleed the coolant system before running the van? A lack of heat from the heater seems to indicate an air pocket.

Does the white smoke smell "sweet"? If so, you are burning coolant and may have blown a head gasket when the van overheated.

[trect]

thanks for the quick reply.

well the CEL no longer comes on while the van is running and there is more water than coolant in the system right now so im waiting for him to get antifreeze to start the car again and the smoke has a strange smell to it i wouldnt call it sweet. do you think it could be the CTS or the TB gasket?