not sure the best way to describe this....
when accelerating, usually with a load or up hill but not always,
there will be some smoke which i figure is normal,
but then occasionally there will be a quick puff that blows out bigger
and darker than the steady stream which i figure is normal..
make sense?

this doesn't happen often, but i'm concerned about what causes it.

 

Bump in the road makes your right foot jump a bit?

 

May also be an early indicator of a sticking injector. I had that issue with an older truck of mine, an 89. But it would be at WOT where I would notice the nice grey haze would have puffs of black that would fill a 5gal bucket. It was finally found that an injector was sticking.

 

i rarely floor it, but it is usually only under pretty heavy acceleration...
are there any other symptoms of a sticking injector?

 

also, i do notice some additional smoke when pressing on the pedal, but this is different. it's like a real quick burst of smoke above and beyond the normal exhaust, and without any changes in acceleration or sound or anything...

 

These old mechanical trucks need to be "beaten on" once in a while to keep things clean(no joke). Might want try that if nothing else seems to help.