I have a 1994 F-150, in-line six, automatic, 4.7 liter, 235k miles. Recently, it has given me trouble trying to start it. It will turn over, but it won't fire and just begins to shake violently. I have to turn the key multiple times before it will fire and start up. After it starts, I have no problems with it. It won't die when I'm driving it and it runs fine. It's just the initial starting that is the problem. Hopefully, I've given enough information.

 

I am not sure I understand what you are saying.

Are you saying the engine does this while cranking?
If so it sounds like a bad ring gear on the flex plate or fly wheel.

Or are you saying the engine is kicking back as it is cranked?
If so then you may have a timing problem. You would need to pull the SPOUT and put a light on it.

 

did have this problem on a van inline six
spark plug wires cap--were in poor shape--only happened when we would have very wet weather though-would spit and buck after it started though until it dried the wires/cap
might be worth looking at them