Need Help, S60 Sputtering after new plug install

[crsny]

So today I decide to change the air filter and spark plugs in my wifes 2004 S60.

I put in NGK #6418 plugs and STP SA9073 filter. I also gently pulled the MAF sensor out and cleaned it and screwed it back in place. The plugs were tough to get out they were pretty frozen I used a little WD40 to soften them up so I would not force them out and break them.

After I was all done I started the car up and it sputtered and ran rough. I figured it would take a minute for the car to get used to the new plugs so I took it for a spin. I didn't think I was going to make it back home. The check engine light came on blinking and I had a message that read "either slow down or shift up" on the message screen.

Any ideas what the heck is going on?

[crsny]

Thanks anyways, I figured it out. I went back through the plugs and found the problem.
It was one of the plugs on the coil that had come loose and was only partly connected.
Once plugged back in it ran smooth as glass.