2003 Discovery

1. Changed Plugs 3wks ago to uridium
2. Changed plug wires to NGK last week
3. Codes Showed PO300 + P1300 Ignition Timing after cleared
--Prior to Clear Codes showed PO301 + PO 307 #1 and #7 cylinder missfire
4. Seems to be running rough still slightly at idle and fuel mileage still down from before changing.

Any suggestions other than pulling no1 and no7 plugs to verify not fouled nor spacing incorrect to what else to check or could possibly be?

Thank you.