I have a ford ranger 3.0 and it has low rpms and is getting hard to start for one. Two I took it to advance auto and they put it on there machine and it said codes po171 po174 but they could not tell me what they meant. So I looked it up and it said it could be a number of things. I have no vac, leeks and checked the mass air flow sensor. I'm not sure on what to do next please help.
I think you need to check again for vacuum leaks. I have fixed many a Ford with those codes and 95% of the time it is a vacuum leak. It's usually one of the vacuum elbows or the PCV hose rotting out and sucking a hole through them.