When we migrated from Pardot to Marketo, we had a similar issue and it ended up being some scripts on the site we had running in the background were interfering with marketo munchkin code from running, or making the munchkin run slower and by the time the user clicks to another page, we lose that original referrer and end up with our own site as the referrer, which was wrong. Once we identified the problem scripts and cleaned them up, munchkin does run much smoother and quicker, and we are able to identify our referring urls much more accurately, but we still do have that problem about 10% of the time. 😕 I think it loads a little slower than the Pardot code for whatever reason.
If you follow me on the Community, I can send you an experimental Munchkin extension that will drastically increase the accuracy. The others who are testing the code have reported up to 150% more activities registered.
Hey Sanford, That sounds interesting, thanks for speaking up. Have you found any negative impacts anywhere else in Marketo or other by implementing this extension? if not, I'll definitely give it a try.