Need help, truck won't start !!!!

[woodrow59]

Got off work tonight and truck wouldn't start. Starter turns just fine and it's gettin' fuel. Figured the only thing left was it's not getting fire. Checked the wires around the coil and dist. and they all look good. Traced the wire from the coil back to the ignition switch and it was spliced in to a wire going to the switch and wrapped with electical tape. I took the tape off and it seemed to be connected fine. I then saw a small wire I think was yellow (it was dark and I was using a flashlight so not sure) coming from the switch . It had insulation missing around it and the wires looked a little weak. I tried to twist the wires together a little to make sure it was connecting. I also wiggled the rest of the wires going to the switch . The whole time I kept turning the key to see if it would fire and sometime in there it started and ran for 30 seconds and then died. I messed with the wires some more but no response. I've only had this truck 2 months but it's started fine until the last couple of days. It's been taking longer to start after I turn the switch. Is it the coil? Can they go bad gradually?