I would only be guessing, so let some other people comment before jumping into it
i would guess at a vacuum leak
could be hoses, you could spray WD-40 lightly along the hoses & the intake manifold while the engine is running fairly smoothly
if it picks up speed or tries to die out, likely you found the leak
another possibility is the plenum gasket, if it turns out to be bad, pick up the kit made by
HUGHES
http://www.hughesengines.com/Index/products.php?partid=26190
i would guess at a vacuum leak
could be hoses, you could spray WD-40 lightly along the hoses & the intake manifold while the engine is running fairly smoothly
if it picks up speed or tries to die out, likely you found the leak
another possibility is the plenum gasket, if it turns out to be bad, pick up the kit made by
HUGHES
http://www.hughesengines.com/Index/products.php?partid=26190