timing issue maybe
How do I check the timing on a 2005 f-150
I thought it might be a starter issue, turns
out my starter is fine. Now it wants to turn
over real slow and backfire
Crank and cam sensors tell the computer the location of each cylinder, so if they get get out of specs it can cause timing problems, I have also seen about 2 ECM's go wacky and cause an over advanced spark. To test all of this properly a lab scope is highly recommended, so if you don't have one I recommend that you let the pros handle this one.
Search Ford F-150 Questions
Ford F-150 Experts