we have changed the water pump radiator cap the thermistat the egr gasket and it is still over heating willing to try any thing now so any ideas will help seems fine if you drive long distance at 50 mph when you slow down it heats up the fans are working gauge works steam comes from over flow

 

By overheating I assume you mean steam comes out of overflow or elsewhere?
Does the radiator fan ever run? If not, may be blown fuse, bad relay? Does engine temp gauge work?

 

The condition you are describing sounds like it pertains to the heat exchange properties of your radiator relative to airflow. In other words, as you are driving faster, more air is blowing across the radiator , keeping it and the coolant from overheating. As the vehicle slows, it is relying more on the fans to keep air flowing. I would first check all of the fins on the radiator to make sure they are free of blockage (bugs, dirt, etc...). Next, just because your fans are rotating, that does not mean that they are still working at optimum efficency. They still may need to be replaced. Bottom line is, overheating is caused by loss of air flow, loss of coolant (leak), loss of system pressure, or loss of circulation of coolant. It sounds to me like an airflow problem.

 

I would add "introduction of hot gases into the coolant", i.e. blown head or intake manifold gasket, which is usually related to "loss of coolant".

 

I'd be deadly sure about those fans cause I've seen more of them go bad than I could count............Other than that I agree with Tow.I'be be block testing that unit.......With the amount of parts you've installed I gotta ask.....How BAD did this unit overheat????.did it run deep in the red for an extended period of time??

 

If it's the head gasket, you better hope you didn't crack the block - I had it happen on my old '99 Intrigue, and it basically turned that 3.5 into scrap metal - Especially if you run it till it stalls.....THEN it's gonna get pricey.....

Kenny