Sorry to post this issue again. I've read several posts on here about rough idles, but I don't see the same intermittent issue I'm having. On Thursday after driving to a happy hour after work (truck ran fine), on the way home it started idling very rough. Still had decent power, didn't die, but ran really rough at low RPM (like it was missing a cylinder) and had an odd smell, almost like hot electrical, but could have just been unburned fuel. Eventually the SES came on, so I drove it over to a garage. They didn't get to it until the next day, Friday. They said it ran fine, but had a code saying random misfire. They recommended a fuel system cleaning and new plugs, I had them do the fuel system cleaning. Drove home fine from the garage Friday night, but when I went to leave an hour later it idled rough again. This morning (Satruday) I put in 6 new plugs. Truck ran perfect after that, all morning through maybe 20-30 miles, 4 or 5 stops while running errands. The truck sat for about 2 hours after that and when I got in to leave again, it idled rough again.
It seems that if it sits for an hour or two then it runs bad, but if it sits overnight then it's fine again. I bought one new ignition coil and put it in two different cylinders that seemed like culprits: #6 because the old plug was slightly darker than the others and it had a little wetness to it, and #1 which had the coil replaced in 2008 along with a new plug. Truck ran the same regardless of whether the new coil was in or out in either cylinder, it ran poorly. The guy at advance auto told me to test the coils with an ohm meter and showed me how. All 6 tested the same as the new one.
So now I don't know where to turn besides a professional garage (first one I went to was a Firestone that's been good to me for other things in the past. Not so much on this one). I'm assuming tomorrow morning it'll run fine again for a while, but maybe not.
So any advice? Sounds like I may need to clean the throttle body, but that doesn't feel like it'll fix this. Maybe a bad spark plug wire? Not sure how to test that. I've owned this truck for 9 years and I've had minimal issues with it. This doesn't seem like a major issue, just need to pinpoint the problem, so I'd hate to have this be the undoing of my trusted ride. Any help is appreciated.