I have a 04 f150 fx4 with a 5.4 motor. Recently I replaced the fuel pump, fuel filter and a module that is bolted onto the frame above the spare tire. I had to disconnect the battery to clear the check engine light. It ran great for about a week then I noticed that if I shut off my truck and come back a few minutes later it would start, idle rough and low before the rpms would pick back up. It has even refused to start for me. I did a sea-foam treatment, through the brake vacuum line. It threw a check engine light that went off on its own. The truck didnt give me a problem for another week then started acting up again. Any ideas what could be wrong? What are the symptoms of a bad throttle position sensor?

 

I have a similar issue. Mine is a 2004 5.4. It's intermittent and feels like it's kinda running on a couple cylinders...kinda like bad spark plugs or something. Anyhow, I took it into my mechanic after it gave me a code and it reported that it's running too lean/too rich, so it has to be one or the other. The mechanic was willing to bet the farm that it had everything to do with the rough idle. We were thinking about an O2 sensor maybe? It seems other people are having similar issues but not to many people on here have a solution hahaha! I'm going to change the sensor and see if that helps the situation. By the way, what was the module that you replaced next to the spare tire???

 

My 05 5.4 does the same thing - go to start after short trip and it blubbers and sometimes dies then starts fine like nothing is wrong. The dealer could not fugure it out but I do have a K&N CAI and may need a programer like somebody else suggested.