5.7 Ignition/Computer Problems? NEED HELP

[1low4door]

One day my truck randomly decided to not start but would crank. Almost every sensor is brand new. Brand new distributor,wires,spark plugs. My truck will only start with the #3 cylinder spark plug wire unplugged but will only crank over and not start with the plug on the spark plug. I have no idea what this could be. Truck will only turn over by me crossing over the starter. Key won't start it.

1999 Crew Cab Short Bed
5.7 w/ 4l80
5/7 drop

 

[DustyNova400]

Try changing the ignition switch in the column

 

[1low4door]

If anyone else runs into the problem it was the distributor cap. If your truck will crank but won't start, unplug the #3cylinder spark plug wire from the spark plug ( the second from the front on drivers side ) and if it cranks it is most likely your distributor cap!

 

[alpinecrick]

If anyone else runs into the problem it was the distributor cap. If your truck will crank but won't start, unplug the #3cylinder spark plug wire from the spark plug ( the second from the front on drivers side ) and if it cranks it is most likely your distributor cap!

What brand and how old was the cap and rotor?