Question about SES light in relation to possible bad coil on plug

I have a 2001 GT automatic. I suspect that I have a bad coil on plug or possibly a bad plug. The symptoms include bucking/jerking at low rpm when using very little throttle. This bucking/jerking will also happen sometimes while sitting still at idle. There is no associated change in RPM when this happens. The car seems to accelerate fine when I'm on the gas however sometimes I can hear a faint low "pup pup" type sound while accelerating hard. The problem has been occurring intermitantly over the past couple years and seems to be more prevalent when the weather is hot and humid. The SES light has never come on at any time. I know it's not the MAF or IAC as I've investigated those already.

Shouldn't the SES light come on if it were a bad coil/plug? Given the above info are there any other possibilites you can think of? Thanks for the help.

That's likely what I'll end up doing although I'd rather not have to change all the C.O.P's if they are expensive. Even so, if the plugs or the coils were the problem shouldn't I be seeing the SES light?