Hmm, I think if it's still reading out by miles, then it's most likely the sensor itself has gone, which as you'll have read in the article, is common thing for e36's. Have a look for a 2nd hand one from a breaker's or Ebay. Did u get a replacement sensor or air duct?
A new one from BMW is like about 100 quid!! Also, make sure the contacts in the plug are clean too, that could affect the sensor too.