scensor Failing?

Vauxhall Zafiria 1.8, 187 cap, after 3 miles each day , at same place lose's power and can't rev up, goes really slow, so I pull over and turn of, rest few minites , then it works again .
was told by diagnosing is the scensor that sends a message and opens valve to release petrol, but garage not got back to me and not give me a price, what to do.