1988 Ford F-150 starting

If the timing is off and the ignition is firing too early, it will make it hard to start. However, how does the engine run when it starts? If it is ok, then timing most likely isn't the issue. When you crank the engine, do the battery terminals get really hot? Have you checked to make sure the terminals are clean and tight and the ground to the engine block is the same? A bad ground could cause this too. Finally, if everything looks good, I would recommend having the starter tested. IF it is drawing too many amps, it will crank slow and kill the battery fast.

Let me know if you have other questions and what you find.

Joe