Any suggestions on were I can get a decent the air flow sensor for the disco1 it’s sits along after the air filter.

 

try ebay

 

I picked a spare from the scrap yard. A wrecked vehicle was running when it crashed. Tested (signal voltage at certain RPMs) good, same as a known good unit. Will Tillery (aka Rover Guy Parts) will have one. But your high RPM problem is probably not because of the MAF.