I own a stock 2007 mustang Gt with the 4.6L I have had it for almost a year and just a couple of months ago I started having problems and my check engine light came on and I pulled the codes and it said that I had a cylinder 3 & 4 misfire and Bank 1 Too lean and Bank 2 too rich so I changed the plugs then it ran fine for a couple of hours then the light came back on this time it said I had a random misfire and a misfire on 3 & 4 and a O2 sensor stuck lean Bank 1 sensor 1 so I swapped the 3 & 4 coils with 5 & 6 and reset the light then it came back on and it said thar Bank 2 Too lean and Bank 1 too rich and ignition coil E & F Primary/Secondary Circuit so I reset the light and then a day later the light came back on and again too lean Bank 2, too rich bank 1 and a random misfire and misfires on 2, 3, 4, 5 & 6 so I reset the light and an hour late it can back on everything was the same except for it was not misfiring on 2 & 3 & 6 so I changed the coil on 5 and swapped coil 4 with 6 and reset the light then it came on again and it said this time bank 2 Too lean and a random misfire and a misfire on 6 & 8 so I checked the PVC tube there was no cracks so I cleaned it and put it back on and reset the light and again it came back on with Bank 2 Too lean, Bank 1 Too rich and a random misfire and a misfire on 6 so I changed the coil on 6 and I ran good for a a few days the the light came on again this time it said the same thing about Bank 1 & 2 and that there was a random misfire and a misfire on 1, 3, 6 and 8 and ignition coil E primary/secondary circuit so I cleaned the Throttle body and changed the fuel filter and put injector cleaner in the gas and I ran fine Except for third gear about 3000 rpms then the light would start blinking and would go off then about two hours late it came back on and stayed on and it said again the same thing for Bank 1 and Bank 2 and a random misfire and a misfire on 1 & 8 so I looked for vacuum leaks and could not find any and the mass air flow sensor looks clean so I am out of ideas on where to go from there please help

 

I deleted the duplicate post as you requested and moved this one out of the "handling" subsection

 

Have you done any recent work to it?
Were there any other problems before this started or things going on that you were ignoring?

Given the lean/rich bank keeps flip/flopping and that you are having multiple random misfires I'd be looking at three things, all electrical related.

1) wire harness is shorting out somewhere. There are several pinch points along the length of the coil/fuel injector wiring harness where it could have rubbed through or broken through the sheathing. Also, get under the car and check the O2 harness for similar wear/breakage.

2) PCM is bad. This is less likely and more likely to do with scrambled signals being received by the PCM from a wire harness that is messed up as mentioned above

3) Check the SJB in the passenger kick panel for corrosion/rust or any signs of wetness. 05 to late 06 build cars (sold as 07's) were known to have water intrusion issues in that area.

 

possible alternator going bad? if you need one, get one for a 2010 model in either auto or manual, whichever applies.

 

I replaced the alternate this summer

 

i have hit some big pot hole and I live down a gravel road so maybe something could have broke one of the o2 sensor wires and I am not to sure if the SJB has gotten wet, I am going to replace the intake gaskets and the injector O-rings so I will check for brakes in the wiring harness.

 

just because you replaced the alt, doesn't mean its still good. a bad diode will send a/c ripple thru the wiring (usually this throws cam sensor codes at first) and interferes with the data some sensors are sending and the ecm interprets that data as an issue and sets the codes and MIL. an alt can also bench test good and still be bad. electrical gremlins in these cars are a pain to chase down. good luck

 

i found the problem I had 5 spark plugs that the ends broke off of and where causing the misfire

 

Mmm..you sure the plugs didn't break when you tried to take them out to check them?

Did you already replace them and confirmed it fixed the problem? If so, I'm wondering how they broke in the first place? They don't just break unless someone tried to remove them and left them as they were and didn't tell you about it.

 

I found the problem it blow the tips off of 6 out of 8 of the plus talked to the parts store and they said it is normal with the motorcraft plugs replaced them and has not had a problem for three months know it is acting up again any recommends on god set of plugs