My 04 Heritage with the 4.2 has undergone a lot of work since I bought it. It has right at 98k miles. Ran perfect for a while, but has developed a sputtering issue after it warms up. It also splashes back fuel wen putting it in the tank regardless of how slow or fast you go. Takes about 15 minutes to fill up because you have to go slow, then stop, then start and stop.
As for the running bad issues, I have these codes: P0442, P0172, P0175.
0442 is a leak in the EVAP system
0172 and 0175 are both for a rich air/fuel mix. I am guessing these are all related somehow. Research on the rich codes suggests the CATs and/or O2 sensors are the culprit. As for the EVAP system, I am not sure what I need to be looking to replace. I did go full crazy person and take the bed off to see if I could figure out the fuel splash problem. Pic attached. What are the 3 things shown called and would they be a major contributor to my problems?

 

OK so #1 appears to be the Vapor Canister Vent Solenoid and #2 is the canister. So what is behind door #3? And I can't get the lid off the thing.
I am also thinking I am gonna need to look at the Vapor Canister Purge Solenoid which is IDK where.
Gonna take the canister and all that off after work and try and see if those lines are clogged.

 

P0172 and P0175 say too much fuel delivery, I'd say you got a stuck injector , I had these codes, I pulled out,cleaned my injectors by powering them open with 12 volts and sprayed em clean with carb cleaner, black junk came out, when I put them back in all those codes went bye bye, I was chasing my canister too,it was not that. Or just buy new Motorcraft injectors if they are older than crap.
P.S. Make sure your air intake setup is not getting a leak ,this can throw these weird codes too. Just from my past code findings.

 

Hey M, (or anyone,) at 100% duty cycle, do we need a ballast resistor? Did you use a battery, or a charger, (which would exceed 12Vdc, IF a modern charger would even turn on.) Is there a time limit, like, 15 seconds, suggested? TIA

 

Sorry bout that I used an Astron 12AMP fully regulated power supply, but a 12 volt wall wart thats D.C. worked too, do not leave the wires on after you spray the injector , the injector isnt meant to stay "Open" for that long. You can not kill the injector it just gets warm if you leave it on along time.
~I used the Autozone brand cleaner , and their electrical cleaner on the connector pins . When you apply power to the injector it will click .
a sure way is to stick on the little red plastic hose and put the hose in the top of the injector and spray while having it energized.
alligator clips from power supply to injector pins.

 

The rich codes are probably from the stuck EVAP parts. Your intake is sucking fuel vapors through the system. Saw a video about it somewhere out there on a different model. EVAP system causing rich codes.

Fix the EVAP problems before you go off an injector tangent. One fix might remove many codes.