trying to trouble shoot an engine miss without electronics.... miss just started today out of the blue and is pretty much only at low RPMS, with truck running I pulled connections at each COP and miss got dramatically worse, so i started looking for vacuum leaks, none found. next I went to MAF I did not clean it, but unplugged it and no change happened, can I take it that I either need to clean MAF or should I go ahead and buy a COP and start with #1 and work my way through? any thoughts would be greatly appreciated. oh and it has a new fuel filter, engine has 87K on it

 

Could you possibly have a sticky IAC valve and might mistaken it as a misfire? A stuck IAC valve at low RPMs when the engine is cold will sputter.

 

Checked the IAC seemed to be ok, so I bought a COP. all the posts on here seem to point that direction. only had to get #4 before I found the bad one LOL Thanks for all your insight this sight is a lifesaver!