Ford Courier XLT unresolved problem

I seem to have an unresolved problem with my 2005 Ford Courier XLT dual-cab petrol ute which has now done 204,000 km. Recently the overdrive light started flashing and the engine light came on, and the ute immediately went into limp home mode. When my mechanic checked he couldn't find anything wrong with it, and it was running fine, but the car only went 500 metres before the problem resurfaced. Six weeks later I was told the car was now fixed and running. The problem, I was assured, was a loose connection in the airflow sensor. This time it lasted two hours before the problem came back. I am not sure where to go from here; the local mechanic has had the ute for a total of seven weeks and charged me $1600 for repairs that haven't rectified the issue. Where do I stand with having paid $1600 for repairs that didn't fix the issue and where should I take the ute now for further investigation? Should I go to Ford or an auto electrician and do I have any recourse on the local mechanic?