My 2003 LX did what you are describing everyone once and a while before it dropped the valve seat. It would start acting up, I would turn it off and restart it and it would be fine for a while.
Will aka Misfire
2010/2011/2012/2013 Ford Master Certified Service Advisor
2003 LX "traded in"/2010 SES "traded in"/2012 SEL Hatch "current"