Okay, I know there are a gazillion misfire threads on here, and I've been chastised once or twice for not using the search button, but after 2 days reading through countless other threads regarding misfires, I haven't really been able to find enlightment.

Here are the symptoms:
When I bought the truck about 1.5 years ago, it had a slight miss at idle. It would miss fairly randomly. I changed plugs and wires, and it didn't really do fix the problem. I let it go for a while, and then it started missing with more frequency, but still only at idle. At this point, I replaced the dist cap and rotor and did the plugs again (champion copper). Still, no improvement. About a month later, I started feeling a sputter under light acceleration (when it starts sputtering, I can usually get it to stop if I really step on the gas), and the truck started to feel like a washing machine on spin cycle every time it idled. CEL came on for a couple of days and then turned off. I took it to the autoparts store to have the code reader hooked up and it came up with stored codes for a pre-cat O2 sensor and misfire on cyl 7. Changed out the sensor and took it to the shop to have the misfire diagnosed. They said there were no vacuum leaks, compression was good, and spark was good. They thought it was the injector on cyl 7 and replaced it. Still nothing. After reading countless plenum threads, I checked into it and saw that I had oil in the intake, so I did the plenum gasket and plate. Still nothing. THEN i started noticing another problem - now that it's started getting a bit cooler in VA, when I leave for work in the morning, even after letting it warm up for a few minutes, the first couple of times I give it gas, it revs up, but has almost no power. It will still move, but it's a lot more bark than bite. Usually by the time I get down the driveway leaving my development (about 100yds) and onto the main road, it will go back to "normal". I've read about crank position sensors, valve seats, cracked heads, yaddy yaddy yadda and whatever million other things that can cause misfires and rough idle... SENSORY OVERLOAD! Is there ANYTHING anyone can think of that could possibly cause this series of unfortunate events? The truck has about 180k miles on it.

 

Try taking the pre 02 sensor out and run it, might be a plugged cat.

 

+1

 

I think there's a very strong chance it's your crankshaft position sensor. Read the thread I started called "Interesting spark problem". My CKPS was faulty, but hadn't failed completely. Weak and intermittent sparks on certain cylinders. Most tempermental when it started to get cold out.

You can get a perfectly good one from NAPA for about $60. Take yours out and ohms test it against the new one so you won't have to risk wasting money - but I really think there's a good chance that's your problem. Please let us know if that was it.

 

Thanks for the input. I actually was starting to lean toward the Crankshaft sensor from what I have been reading. I havent tried taking the o2 sensor out yet either, but I'll give that a shot as well.

 

Remove the o2 first. It's an easier and less expensive alternative to try.

 

Zman - Agreed. I just haven't done it yet because it just seems like every time I have the time/motivation to do it, I've just come home from somewhere, and I'm not a fan of 2nd degree burns...

 

I hear ya man. It may very well not be the prob, but it's worth a shot.