Hello all, I have quite the puzzler today. I have a 2004 F150 FX4 4WD 132,000 miles, that I've been chasing a Code for the past 3 months. Initially it was a P0175 and misfire P0308/P0316. Now the computer doesn’t know what’s going on since I’m getting both lean and rich codes: P0175/P0174. There is no noticeable effect on drivability and I can't feel the misfire while driving. After resetting the codes it takes on average about 60 miles to actually trip the light again, independent of start and stops. I've noticed that it tends to trip the misfire on deceleration after I come out of cruise control or initially braking from a constant speed. But I would classify it as pretty intermittent. Things I’ve done to diagnose with no success, each item done 1 at a time with a battery-reset of the computer (in order which I completed them):

* Ran seafoam through a few tanks of gas.
* Replaced the fuel filter.
* Cleaned the MAF meter.
* I swapped my 1 and 8 coils, thinking I might have a bad coil in 8 causing the misfire.
* Replaced O2 sensors, both banks, upstream and downstream of the CAT.
* I replaced the injector in 8, thinking there was something wrong with the injector causing the rich/lean code.
* I removed my AirAid intake and returned it to stock. I was planning on removing the intake for a while due to the highway drone affecting the drivability at higher speed (It’s for-sale btw). Installed with new OEM filter.
* Replaced sparkplugs (second time – first at around 100k), SP515. 2 of the 8 plugs were SP507 and others were the older style –I returned the old plugs to the dealer in a bag and told them to figure it out. I decided not to complain too much since they all came out without an issue – different style plugs and batches irritated me a little though.
* Checked all wiring for loose connections and shorts.

I’m still getting the codes. I’m running out of ideas. Any advise or ideas on what to try next would be appreciated!

 

Examine it in detail for vacuum leaks and unmetered air.

 

Freeze Frame Data P0175
Fuel Sys 1 CL
Calc LOAD (%) 20.3
ECT(ºF) 181
STFT B1 (%) -0.7
LTFT B1 (%) -4.6
STFT B2 (%) -14.8
LTFT B2 (%) -27.3
Eng RPM 1238
Veh Speed(mph) 51
Spark Adv(º) 12
IAT(ºF) 32
MAF(lb/min) 1.358
TPS(%) 13.7
O2S B1 S1(V) 0.085
STFT B1 S1 -0.7
O2S B1 S2(V) 0.680
STFT B1 S2 NA
O2S B2 S1(V) 0.330
STFT B2 S1 -18.7
O2S B2 S2(V) 0.835
STFT B2 S2 NA
FP/Vac(psi) 39.6
ECU Volts(V) 14.551
Rel TPS(%) 2.7
Command TAC(%) 4.3

 

Check this out, had some similar issues myself and this was the culprit.
http://www.ford-trucks.com/forums/10...any-ideas.html