Ok guys, first thing I wanna say is I have been doing some reading on the site. I spend a lot of time in a golf forum and I get to try real hard for your answer before starting new posts. I didn't find my exact issue and I'm spend money "trying things" instead of fixing.

I bought a 05 f150 Stx 4.6 with 400k miles on it. Believe it or not it's a clean truck all highway miles. I've had it two months. When I first got it, it had check engine light for bank 1 lean p0171. The previous owner was a mechanic. He claimed to have replaced spark plugs. The truck hesitated on acceleration, and although it ran, it didn't idle well or have any power. He bought a fuel pump motor, fuel filter, maf sensor, and a 4 could out of Lincoln town car (apparently same 4.6l motor) on my dime. After replacing these things, it ran like the same, and then he realized one of the plugs was off on bank one, the furthers back cool over plug wasn't plugged in. After plugging it in I drove it it had power I hadn't seen before. Ran smooth, no issues, and for once could get up a hill with ease. Felt like a new truck. I paid and went on my way. About a day later, it started to not start in the am, and then not start when I left it for more then like an hour. It also started not running right and idled ****ty again. The truck started running with misfire, and then would randomly hesitate on the highway mostly until I stepped on the gas to the floor for power and it would accelerate well and then run ok for awhile and then need be done again. It's all random but guarantees to do it each trip. It's very much less noticeable under 40 mph. At stop lights you can feel the misfire but it's not severe. The same code came up, but I think another came on p0300 or something like that I forget that one. I been saving to buy all new coils and spark plugs and filter and sensors and 02 Sensors to just go down the list until it's fixed but I can't afford it. I literally have to prime it 3x and pump the gas when I cold start it to not be embarrassed in s parking lot. If I cold start no pumping it takes s good 10 seconds to start on its own. If I drive it, run into a store and come back out and start it, it starts fine it's only cold starts. Any ideas? I prolly will replace everything on bank one, but the fuel pressure test was somewhere around 45 at the fuel pump under driver side door , my mechanic guy checked it but idk why it's not starting cold without priming. Anyhow any suggestions would be great. Also want to note since last week it has gotten worse on idle, I started replacing spark plugs I did the front 3 on the bank 1 and it had no difference. I have all 8 but I simply can't get bank 1 the furthest back out. I took pictures of the hole and the but is covered in gunk and I need to get compressed air in there or something to blow it out cuz there's not nut showing. I can post a pic of I can figure out how to. Suggestions?

 

https://flic.kr/p/Nsr4yq

 

Check out the temp sensor, when the engine is cold, it needs a richer fuel mixture to start easily. In the old days that was the function of the choke, now the pcm just sprays extra fuel thru the injectors. If the sensor thinks the engine is warm, it would explain your hard starting when cold.

 

Ok makes sense for the hard starting, any ideas on the misfiring?

 

You can swap around your coil on plugs, then if the misfire moves, you know which c.o.p. it is. Only move two at a time. Then you can try the plugs if needed, also 2 at a time. It's also possible you have 1 or more bad injectors. If none of these solve it, look into mechanical issues, like a burnt or bent valve(s) or even broken or worn out rings

 

I would guess that it is a fuel injector or the fuel pump going. The harsh starts are an indication. Try turning the key to the run position a few times before starting on a cold start to build fuel pressure. If it starts right up, you have a pressure leak down. Then you just have to determine if it is leaking into a cylinder through an injector sticking open, or into the tank through the check valve on the fuel pump.

 

Have you checked the FPDM for corrosion?