SES going crazy

Lately my SES light has been going crazy and the cars been misfiring bad. It runs fine until it gets up to operating temp. I've been counting how many times the light blinks and its always 6, 10, or 15. It's only got 60k on it. Im think coil pack, or plugs and wires. I don't understand why it acts up only when it's hot though. If I got a 160* thermo I think it would run fine but I want to fix whats wrong.

The coil is a possibility. My car only has 53K on it now, and I had to change the plugs and wires at about 40K and had to replace the coils at about 45K. She runs fine now, but just letting ya know my experience and that that could be your problem.

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"Because who really wants to be normal anyway."
1998 Camaro 3.8 V6
Sebring Silver
Whisper lid
Flowmaster dual exhaust
Chrome tips
-check link for pics-
http://community.webshots.com/album/42820231QFLrNI

Is it alright to replace just one coil pack or should I change them all at once? How much are they? Also should I change plugs and wires at the same time or will it be alright? I'm sure the plugs probablly pretty bad if it has misfired alot.