i have a 1997 f250 hd with the 460, the other morning i fired it up and it ran for about 10 min idling fine, then all of a sudden it started running really rough like it was only running on a few cylinders, so i started pulling plug wires and the first 3 did nothing and the fourth killed the engine, so i checked spark and it has spark, i pulled plugged and there wet so its getting fuel, i checked fuel pressure and it has 40 psi, koeo, its been tuned up within the last 6000 miles i checked codes and had nothing, im baffled, any help would help me out greatly guys!!

 

I'm suspecting a weak coil, does anyone have any suggestions on testing it to see if it putting out a weak spark?

 

When you checked for spark (I'm assuming you held coil wire close to an engine ground) was the spark a nice bright blue=good, or was it orange=not good?

 

It more of a orangish yellow color