[mattfranklin]

Sometimes dirty valves can cause stumble. They act like a sponge. So on acceleration they are soaking up the accelerator pump fuel and not letting it get in to help combustion, during the transient, when it needs it most.

My go-to easy fix for that is Techron Concentrate (a couple of jobs ago I did a lot of dyno testing with Techron). It cleans dirty valves, carburetors, (and if you have injectors, those, too.), and combustion chambers. Put in a bottle at the recommended dosage and drive it normally until the tank needs refilling. Do it again, if you think it needs it.

If you decide to do this, make sure it says "Concentrate" on the bottle. That's the good stuff. The cheaper ones are made to compete with cheaper competitors at their level.

That might not be it (but again it might be) , but it's a cheap easy test and then you know you've covered all of the bases.