Engine running rough while idling

2002 Chevy Trailblazer running rough when idling, especially when its cold and it sometimes hesitates. The engine sounds like it is missing. Thought it was because I got some bad gas but still having the problem.I have replaced the fuel filter, spark plugs, ignition coil #2,4,and 6 and 2yrs ago the throttle position sensor. When i replace the fuel filter i notice the gas that came out of it was very dirty. I have also used the fuel injector cleaner a few times when I filled up with gas.What else could be making my engine run rough?

Welcome to AF, no codes or check engine lite? Rough is vague, is this a misfire how is it under load say in o/d at 50 up?

No codes came up and check engine light didnt come on. The running rough is a misfire. I'm not sure what you mean by o/d? Perhaps overdrive. Over 50mph it runs okay, seems to be lacking pep in acceleration.

Yes under load in overdrive, anyway a scan looking at misfire counts should point to the suspect cylinder, ,bad plug, coil, injector,or low compression in that cylinder are all in the mix.