rough start

[292cclb]

hey everyone, i've got 77 crewcab with a 292-6. i go to start it up in the morning and it starts up fine but after about 5 sec. it starts to lope or idle like a harley, real slow like. then after about 5 mins. or so of running it starts to run smooth. could it be the timing is out or something? all vacuum lines are hooked up. i changed plugs sun. and one wire was white (metal connector) on the dist. end, could that be another reason? any info would be helpful. thanks