I get spark from my spark plug wire sometimes when I don't the jeep don't start
Why I don't get spark sometimes?

What's the year of the jeep
... could be a voltage regulator if its older
... maybe a coil
... newer 1 might be the spark management control
... old wires... old plugs... bad connections on the ends..
... bad ground

What have you tried so far to troubleshoot problem?