My trucks runs real good and then when you turn.

2007 Ford F 150, intermittent starts, this applies to whether you are a 4.2, 4.6 or 5.4. If you have a check engine light or a pending code that would be a great start. If it was a crank sensor failing you will code up as crank sensor "A" circuit malfunction, A FRP sensor is suspect but will allow a start up and code up but will stall the vehicle, A failing fuel pump can cause a intermittent start up, This is tough to answer but a good thing is Ford has a KOEO (key on engine off) code capability, you will need to have that check out, other than that this is a shot in the dark.

When it doens't start do you mean it won't turn over or won't run. If it won't run scan for codes and check fuelpressure if it won't turn over check to see if starter is getting same power as battery gives out check starter relay and fuses underhood