Slow crank no start I have an 04 f150 I was going down the road one day my truck just shut off when I try and start it it turns over really slow and doesn't start I've changed battery,e asalternator also when it turning over it makes a knocking sound coming from the motor but the truck won't start only turn over really slow please help

 

Is the oil level up where it should be?

Sometime poor connections can do this.
Did you check both battery cable connections where they connect to the engine and provide power to operate the engine and the rest of the vehicle?

Checking means '''remove them , clean the connections , then reinstall them..
There is a junction connection on the driver's side inner fender in the engine compartment that brings power from the alternator to the battery. If that junction post is rusty and dirty. power from the alternator and battery cannot get to the rest of the vehicle.

 

With the addition of abrupt slower cranking and engine noise while cranking, a change in valve timing from timing chain issues comes to mind..

 

You might do or have done a compression test and that should either confirm or eliminate a timing chain problem.
Usually if timing has jumped a tooth or more, compression goes out the window and the engine spins over faster.
Not too sure that is the problem.

 

I have the same problem on my truck right now, did you ever fix it and how did you do it because the exact thing happened to me a few days ago.