I have a rough idle more often when my truck is warm. For instance I started my truck after work and drove it for about 1 hour stop and go and shut it down a few times and back on and it idled rough that hole time. Not super bad just rpm's bounce a little and it shakes every once in a while. I did find that one of my spark plug wires was sitting on the exhaust manifold and when I inspected it, it was burnt a little on the outside and i bent the cable and it was cracked. I'm wondering if even after patching this part of the cable with some good electrical insulating putty and tape if I could have damaged the wire already and that might be causing an intermittent misfire. I am also wondering if the fact that it seems like it runs smoother when cold if that tells anything. I did also replace the IAC valve when I first bought the truck foolishly because it did have vaccuum leaks, but that didn't affect it for more than a couple years. I did do plugs rotor and wires about 1.5 years ago. any suggestions on next steps would be greatly appreciated. I am thinking about replacing the wires just to rule that out and because that one is damaged, if that is logically a possibility.

 

Replacing parts blindly doesn't rule anything out - it usually CREATES new problems.

The only way to rule anything out is to TEST it; including any replacement parts. Click this & read the caption:

(phone app link)


If you suspect ANY problem in the ignition system, go to the NEXT image in that album and read the whole caption (a few times).

 

where would you start looking based off what I said? Checking the resistance of the wires is easy and I will do that and report back but just wondering where you might start based off of symptoms?

 

Exactly where I said: that diagram's caption, and the NEXT one's. The more tests you do, the more likely you'll find the actual problem. But do the exact tests in the order described - don't jump around, other than as directed by the results you get. Also: make sure your meter has good batteries, or you'll just confuse & aggravate yourself.

 

thabks Steve, I started reading through the steps and it seems after you check the wires it asks if you have completed the EEC-IV quick test. I’m wondering what that is because after I check these wires that’s my next step?

 

It's linked in that caption right below those words.

 

I was worried you were going to say that, I actually have looked up and down that page and it’s not clear to me what they are even troubleshooting, it starts by saying to jump out a connector that turns the fuel pump on... I’m very confused by that page, then it lists a bunch of trouble codes but I’m not getting a CEL coming on and I know the bulb isn’t out cause it does the self check when I start the truck any clarifications would be greatly appreciated

 

Get some sleep & re-read it. I know what it says because I compiled that information over a decade ago, and uploaded it into that caption. Thousands of people have read that caption, and I assume most of them had to read it more than once to absorb it all. Even I have to refresh my memory occasionally, like 2 days ago when I was working on my '93 F250 5.8L. The line you're focusing on says "...to force the fuel pump on..."; since you're not trying to do that, skip that line. Start with "After warming up the engine..."

Yes, it's a steep learning curve, but you chose to own, drive, & maintain an antique truck. You can download (free) or buy manuals by following the links in this caption:

(phone app link)

 

Would you be willing to talk over the phone because I’m pretty confused as far as where those tests even lead to

 

I changed my spark plug wires and cleaned my rotor and cap and truck is running perfect no more rpm flutter or misfire