Rough Idling, Hesitation, and Misfire Codes

[Jerms]

OK...ok...I have a 2004 Ford Taurus with a dual overhead cam.

2 years ago I bought this car used with 40000 miles already on it. I noticed a slight, I would say now, misfire that was barely noticable. With time it got worse and worse. Now my car idles extremely rough and hesitates horribly.

The codes I have pulled were:

Random misfire
Misfire on start-up(first 1000 revs)
Misfire cyl 2,4,5

I changed the fuel filter, spark plugs, air filter, inspected the wires, inspected and swapped the coils(to see if the problem would follow the coils), and checked the MAF sensor.

After all this I managed to rid myself of the misfire in cyl 5 but the rest remained.
Changed the spark plugs again and managed to get rid of the misfire in cyl 2.
Drove around bout a month and got the same codes but instead, the misfire came backin cyl 2 and the misfire in cyl 4 was now gone, and now I had codes for system too lean on banks 1 and 2 as well. Well I changed the o2 sensor, cleared the codes and it drove like new,......but after 15 minutes, the codes came back as did the noticeable problems.

I'm left with:

Random misfire
Misfire on start-up(first 1000 revs)
misfire cyl 2
system too lean bank 1 and 2

It idles rough and hesitates when accelerating. And I've yet to find a vacuum leak anywhere but I have a hunch its there somewhere. Oh, and I've checked the EGR valve too and.....nothing.
Any thought guys........please?

[easton588]

I have the DOHC as well, 03 with 83K on it. Two months ago i had a misfire on cylinder 5, took it in the shop and the wire was screwed up. Ran great and as of last week, i have the same problem again so I'm "assuming" it's just another wire. You said you checked the wires but i would start there again and just replace them as what I am going to do next week. Just from my experience...