Missing after spark plug and wire change.

I just changed the spark plugs and wires on my 2003 disco 2. It now has just a slight miss. The check engine light came on and says I have a miss on cylinder 3 5 and 7. I checked to make sure these where on the plugs snug. The wires are new so I know all 3 arent bad, I had to replace the # 3 wire 3 months ago b/c it melted and I waited to put the whole set on b/c of the time it takes. So I know that the #3 wire is good. Any ideas? Is there a trick to getting these to not show a miss? I cleaned my spark plugs once and after I replaced them I had the same problem, had to take to dealership. I do not want to do that this time because I do not have the $400 they will charge.