Re: timing problem
As per your email, here's the info on the firing order. As I think back to my conversation with the cam company, the change to the 5.0 HO and 5.8 windsor firing order may have started in about '88 or '89. In any case I do believe that If you wired the spark plugs like the 5.0L truck's sticker says that there will be firing problems. Just remember, since it is batch fire the motor can still run... albeit very poorly. I really think this could be the problem. And when its right, you will love the way that truck runs!
Cylinder Numbering...as you are facing in towards the windshield (passenger side will be on your left and driver's side will be on your right)
FIRING ORDER FOR 5.0L & 7.5L
MOVING COUNTER CLOCKWISE...
1 5 4 2 6 3 7 8
FIRING ORDER FOR 5.0L HO and 5.8L
1 3 7 2 6 5 4 8
MOVING COUNTER CLOCKWISE