Heat and Smoke

[ChevyCK]

All,
I have a '99 GP GT with just over 87,700 miles, 3.8 and I drive approximately 120 miles a day. The engine has been getting hot, very hot, over the past 3 weeks (approx) and the trans shifts harshly when the temp gets around 210. I have even used the heater full-blast to help control the temp.
I had the tranny flushed originally, thinking the fluid viscosity was low, then determined the cooling fans weren't working. I have tested both fan motors and they ops check good. I replaced both relays for the cooling fans and replaced the coolant temp sensor but haven't notice a significant decrease in the temperature.
Tomorrow, I'll be changing the thermostat and getting the rad flushed. Any other tips that might be helpful with this?
In the last two days, when I start the vehicle, there is a significant amount of smoke out of the exhaust, but only last for a minute or two. Once I begin to drive, I no longer see/notice any smoke. What can I do to help clear this up? The problems just seem to be getting worse each day.

[BNaylor]

Welcome to AF.

What color is the smoke? A minute or two of smoking doesn't sound good.

A common problem which may cause overheating and other driveability issues are the upper and lower intake manifold gaskets.

[ChevyCK]

Thank you for the quick response BNaylor. It is white smoke. It doesn't smell too offensive, more like a fog machine; not like a rich or burning oil smell.

[BNaylor]

That is not a good sign. White means you are burning coolant. Have you checked coolant level and for any coolant consumption? Also check the condition of the engine oil?

Pull the #5 and #6 cylinder spark plugs first and inspect or any many as you need to.

[ChevyCK]

Last weekend I checked the coolant and it was full. I haven't checked the oil though (since the last oil change). I recently (in last 2 weeks) replaced the spark plugs. There wasn't any fluid on them.