1984 gmc pickup problem

My truck started running rough when I started it up after I came home from lunch. It feels like the plug wires were switched around, or like it's running on 5 or 6 cylinders, and it's a V8. I also noticed that
the tranny wasn't shifting properly. I know these two problems are related since they happened at the exact same time. I think it's probably a rotor, a distributor cap, an ignition coil or an ignition module. I'm pretty sure it's a spark problem rather than a fuel problem. My question is, how would I diagnose my problem without a scope? I think if I fix the spark problem my tranny problem will go away. Have I forgot anything under the distributor cap that might cause this problem?......ps, there are no computers in my old truck...thanx in advance
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snipped-for-privacy@hishouse.ca says...

Vacuum leak maybe?
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