P0355 means you need to replace the #5 cylinder plug and coil, be very careful doing this since the 04 the first 3 valve engine has a concern where the plugs break off when removeing them.
P2104 and P2112 means you first off need to fix and clear all other codes and if this code comes back then you need to replace the faulty electronic throttle body. Sometimes a fuel system cleaning shown below will help or resolve a throttle body code.
My dealer charges 3 hours to change the plugs then a hour for each plug which breaks off. Yes it will be your money paying the bill. And these plugs are 20 dollars each. The replacement plugs dont have this breaking issue.
If the dealership is honest then they should treat you honest. We do not treat customers like what you mentioned but I can speek for others.
I just fix fords, I dont make the rules as to why they dont recall certain defects.
Yes the plugs should last 100k but if this truck were in my driveway I would change them all now before they get really worn and carboned up and even harder to get out.
I cant make up your mind on what to future purchase. I have great luck out of all 8 ford vehicles I have owned and have 2 in the driveway now and if I got a bad one I feel I would still stick with ford since they can apparently run the funds correct and sometimes you get a bad apple but cant weigh all future decisions based on one.
I have had to get out near 100 broken plugs so far on the 04 and 05 model and have never had to replace or remove the head for this. there was one case where I broke one plug and told the customer it would cost another hour and he oddly refused and drove it home like that and attampted it himself. So he decided to drill it out. Then it came towed back in with a large hole where the plug should have been since he drilled it out like a inch in diameter and then cranked the engine while all that metal was on the piston. He then paid for a new engine. 75 more dollars would have been cheaper.
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