wabbout a busted #1 plug wire? Seafoam is not a miracle cure, but it is fairly harmless. I used it as directed and it did help de-carbonize stuff when I put it to a vacuum line.
I highly doubt the plug wire is messed up from running seafoam through the egr port..cmon. The car was fine prior to this. Seafoam did however do the intended job in cleaning the egr port and relieving a slight midrange hesitation.