Boxster fault codes

[Brucey]

Hiya all, my 986 Boxster (1999 127,000 miles) is running poorly on tickover i.e feeling like it isn't running on all 6 cylinders, however when I set off it seems to run o.k. I've since changed the oil, filter and plugs but still have the same problem and when I plugged in the diagnostics it reads fault code 300, 301, 302 and 303 which I gather is indicating a misfire on one sides bank of cylinders.
Has anyone any ideas as to what my next move should be? All suggestions are welcome.
Thanks, Andy Bruce.

[Sean Smallman]

Coil packs would by guess, check to see if any are cracked.

[Lee 944]

Aye, cool packs. I got a set from Design 911 which were reasonable, I think they were less than £150.

[Lee 944]

Make sure they're the new ones starting with a 997 part number.