Given your past problems, I would highly suggest checking all of the timing marks.

You can start with leaving the lower cover and pulley on, but checking if the cam sprocket lines up with the mark on the back cover at TDC. Also double check the timing mark on the dampner at that point.

With the valve cover off, see where the distributor lines up. There are marks on the shaft and the body that should all line up with a mark on the head (under the valve cover by the cam).

I suspect the distributor is off by a tooth, but you have to go back to the basics to make sure.

As for the cam, you can do a cam swap without tearing off the front timing cover, but...you might as well consider it so you can check that lower timing mark. Besides, if you let the timing belt slip when the cam sprocket is off, you will have to tear it all down to re-time everything anyway.

Good luck,
Michael