Spark plugs are new and gapped to correct space. I am going to put new wires in tomorrow. Its not a big misfire just a little thump every once in a while. Only at idle, while running no misfire is present. I don't know why. I did put higher octane but i doubt thats the problem? Any ideas. I was going to use a injector cleaner and new plug wires.

 

What year?
What model?
What engine?
Does the check engine light illuminate and then shut off during the bulb check?
Is the check engine light on, or does it flash, while driving?
What brand of plugs did you install?

 

2X^^^. Octane..no, injector cleaner..no, good wires..yes.

 

being a bike owner and ethanol blended fuel becoming more the norm I never trust fuel
First sign of a run issue bike or car I dump in Sea Foam fuel treatment mixed strong

If the run issue arises in wetter weather and goes away after warm up I would agree on ignition wires

is there a pattern when the rough idle happens ?

 

1995 Blazer LS 4.3L 6cylinder. Check engine light illuminates and then shuts off when key is turned to on position before i start the car. Check engine light is not on, never has even remotely flashed on, only during bulb check. Auto lite platinums, I tried looking for the AC delco but they weren't available in my area.

 

95...so many questions. You could be running one of three setups and maybe four there's some debate. Capt. has a set of pics, I think, that can help you identify.
Go ahead and put some injector cleaner in on a low tank, it can't hurt. How long have you had this and do you know any maintenance history. Most likely there has been quite a bit of stuff done to keep it running to this point with just a mild hiccup.
As it stands your on the right track with secondary ignition, I believe. Cap & rotor would be real good, Delco please.

 

Alright thanks. See the thing is i bought this car early December off a guy for 500$. He came down from south Dakota so I have no Maintenance history. By the looks of it he ran it in poor conditions with very little maintenance. Alright, I'll get that in soon within the next three weeks. Money starting to run sorta tight, working a part time job and all especially since our hours got cut >_>..

 

Spittybays is right about different systems used on 1995 S & T body. We need to know which system you have so that we can give you correct information to diagnose it.
1. Does your engine look like this?
2. Do your spark plug wires connect to the distributor cap vertical like these do, or are they horizontal?

 

Yeah looks like tha. my boots are vertically placed. Gladly, the slight misfire is gone!! regapped the plugs, some of them were off and set in new wires thanks guys