i have gotten a misfire code and moved the coils around and since havent gotten a cel.. even before i did thiis i have noticed an unsmoothness or a feeling that is wants to pull harder onder wot. it feels like it is not as smooth as it use to be... i have a 1.5 pulley, low temp stat. the motor only has 55k on it and the car has 95k... the plugs were replaced 15k ago when the motor was put in... any ideas???? im considering doing plugs and coils just to rule it out... should i use oem plugs????

 

It could even be something such as a blocked cat.
Now, that would typically distort the fuel trims so you could maybe monitor them. Many other things show up there, too.
I don't see why they have to be OEM plugs but yes you want some good ones. OE are iridium I believe, and apparently not always Denso but can be NGK. I'm doubtful plugs will be the issue, especially if they've only done 55K.