rough idle, hesitation. PLEASE HELP!

[Mustang5.0]

First off, I am a new member here. I have gotten lots of good advice from this forum already and GREATLY appreciate it. Unfortunately, I have a whole new problem.

I have a 2007 Mountaineer with the 4.6L, 72K miles. Today when driving home from work it started shuddering, idling rough and check engine light flashed for a while then went solid. I had the codes read:
P0305, P0307, P0300 and P0316. I got a description of what they were, but I don't know what is causing them, especially the Random misfire. at first I was sure it was a coil pack because I had this problem before, but it was only cylinder 5. Now it's multiple cylinders. I replaced the fuel filter(trying the cheap way out) but that wasn't it. I already replaced all 8 plugs(two of them broke.... that's a whole other story)

Any ideas of what to try without getting raked over the coals at a dealer??? Thank you in advance!!

Kevin

 

[pzy3339]

Inspect your wiring. Start at alternator, battery, and ground points. Make sure all high current electrical connections are in good condition. After this if all is good move on to smaller things, inspect wiring harnesses for crosses and worn wires that might be grounding out or shorting together. It sounds like an electrical issue to me. Most likely some wires have been vibrating together for a long time and worn together at some point where they now touch. You need to find this spot and repair it.

Good luck.

Just for good measure, what plugs did you use to replace the originals?

 

[Mustang5.0]

I used the motorcraft OEM plugs.

 

[Mustang5.0]

I forgot to mention, it cleared up on the way home. just like it did the last time this happened. it is running perfectly now, which will not help in diagnosing it!!

 

[pzy3339]

That supports my theory. Start chasing wires. Free, just takes time and patience.

 

[Mustang5.0]

Thanks pzy3339 for your replies. I checked over the wiring and vacuum lines and didn't see anything loose, bare or abnormal. I'm actually pretty impressed at how clean it is under the hood. no rust or brittle wiring. I guess it's off to the dealer.

I must say, I'm a little disappointed in this forum. I see it was viewed over 100 times, but only one person tried to help. I have viewed many other posts here, and have gotten lots of valuable advice, where many people chimed in with their experiences, but not this time.