Rough idle, loss of power, where do I start looking?

[Bobby Pootz]

Pulled out my 84 305 truck from sitting about a couple of weeks, upon start up, some darker than normal smoke came out of the exhaust and the enigine is rough now, like I cammed it (but I didn't), and there's a loss of power. Like it's shuddering trying to gain speed.

I'm quite the rookie but would like to see if I can fix this before turning to a shop.

Any ideas what this could be? Bad plug? Distributor?

Thanks in advance!

Rob