1999 Ford e-350 7.3 Powerstroke Van with turbo

This vehicles used to get 21 mpg. Over the years it has crept down to 17 mpg and the turbo seems to not wind up. I can hear it spinning but it doesn't seem to boost. I also get soot on the engine as if there is a leak somewhere but cannot find it.
I recently added a Hypertech Powermax to it and got an extra 2 to 3 miles per gal over the road and increased horsepower but the turbo still is not boosting. The Hypertech showed a 047 code for the Back presure Sensor.
The truck accelerates like there is no turbo at all. I can hear it wind up a little so I know it is spinning but it doesn't appear to do its job. There is no leaking oil.

I have read a lot about back pressure sensors on various forums but still am unsure about a couple of things:
1) Can a bad back pressure sensor keep the turbo from boosting even though it is spinning?
2) Can the back pressure sensor tube keep turbo from boosting?
3) Is the back pressure sensor the SAME sensor that controls the cold start valve?

I'd like to not only fix my turbo issue but also fix my cold start issue. In the winter the van will only go 20 mph unless I floor it because of the valve. The valve continues to activate unless I go at least 60 mph. I'm sick of it!
I am not truly interested in an Eliminator as I feel it could cause damage since it gives false readings.

The best prices for the backpressure sensor is $85 from http://dieselorings.com/index.php?pa...cat=23&group=6
Best for the tube is $40 from http://www.dieselorings.com/index.ph...cat=23&group=6

If you know of better let me know
Any info from people in the know is greatly appreciated.