I have recently got an oil change and replaced the following:
- E3 Spark Plugs
- Motorcraft Fuel Filter
- Air Filter
- Spark Plug Wires
- Coil
- EGR Valve
- Fuel Pressure Sensor
And even bought some mass air flow cleaner and cleaned my MAF sensor and the car still idles very rough and I have the following codes:
- P0305 Cylinder 5 Misfire
- P0108 Barometric Sensor Circuit High Input
- P0171 Fuel System Too Lean (Cylinder Bank 1)
- P0174 Fuel System Too Lean (Cylinder Bank 2)
- P0182 Fuel Temperature Sensor A Curcuit Low Input
- P0193 Fuel Rail Pressure Sensor High Input
- P0300 Random Misfire
- P0305 Cylinder 5 Misfire
- P0193 Fuel Rail Pressure Sensor High Input
- P0300 Random Misfire

So far no codes have came up, I have bought a cold air and was running okay but sometimes ran rough such as idle and misfire from running too Lean, now I put my stock one back on today and my car is a little better, went from 12-13 to 15 mpg but the car idles at park under the 0 and when I go to turn my car off, the gauge needle tries to force itself down to it ticks and shakes 3 times

Actually that’s what I was going to ask earlier if anyone knew what hoses would lead to and cause a car to idle? And where are the most common places to check, btw when I have my intake off, my throttle body was relatively clean so that’s one issue marked off and I bought two O2 sensor replacements and installed a couple days ago and it helped the issue but still idles rough

I checked out the link and will do that tomorrow when my car cools down and may possibly put my old spark plugs back in because I got the E3 sparks but people talked about the gap concern could cause a misfire but I doubt it with the e3 because people on here have had goodluck with them and plus my car was running amazing when I installed them then a week down the road everything started to go wrong

Update, my car was getting 13ish to the gallon wit the cold air and now it went down to 11 to the gallon with the stock one back on. yesterday I was driving and it was hot outside, my car every time I pushed down the pedal, my car would shake and feel very sluggish like there is a **** ton of fuel being dumped as if my car is drunk or a heavy drinker but when I go full foot down to make the revs higher, then it balances it self out again and then it goes back to that weird feeling but right now it’s cold (6:37 Am) and no problems, I mean a few little idles here and there but runs better...?

So my idle goes below the very first tick or dash on the gauge... well okay basically when the car is off, where the needle sits at, when running and warmed up, the cars needle is below the position when off and it bounces around there, I heard that a battery and alternator could cause a 05 mustang 4.0 to idle very bad? Is this true

The car has jba headers, and had a sct badge on the dash but I took it off and I also disconnected my negative and my whole battery sometimes to clear the engine light and people said if it did have a tune then that would erase it

Well I mean I doubt it would be a tune issue if it had one or not because it drove mint for the first month and two I had it

I put my stock one back on, and it still had the problems before the cold air, I decided to put 87 vs 89 which I usually get but just wanna test it because when I put a different octane my car feels weird right away with the mixture and then balances it self out