drivability issue

For the sound of it, I agreee with timing. As a test, disconnect the vacuum advance cannister on the distributor and plug the line.Then drive it again. If the studder is gone, you need to take a small allen wrench (one that just fits into the hose nipple on the vacuum can) and adjust the vacuum can. The wrench will seat in the adjuster when you insert it. Turn counter clockwise two turns from where it is right now, connect the vacuum hose back, and test drive again.