Rough idle and stall at lights
 

Hey everyone, first post but I have been lurking for a while, I have an 01 Supercrew f150 4x4 with the 5.4 Triton. I have had it almost 2 years, the check engine light has been on for a long time but only codes were lean in bank 1 and bank 2, no real issues other than a fluctuating idle indicating a vacuum leak. Last month I decided to try to take care of the problem, I got a can of carb cleaner and tried the manual diagnosis but found nothing. I changed plugs and coils and it ran great for 3 days then started running rough again. I changed the pcv valve and MAF sensor, same thing happened where it ran great for a day then rough again but now it was stalling at lights occasionally. I put in a new idle control motor, ran great for a day then back to rough and stalling at every light. I finally broke down and took it to a mechanic who spent almost 2 hours diagnosing then did a "reprogram" which he said was necessary after the MAF was replaced, ran great for a few hours now its back to crap again. I am out of options and at the end of my rope, what else could it be?

Ok you need to do the basics. Install new air cleaner, Make sure plugs are in good shape, check for split vacuum hoses or the air tube that feeds the MAF SENSOR and throttle body. You may have to remove these tubes from the truck so you can check them for rips or tears. This is the basic eye ball everything, maybe even spray a little water on things while its running, Not a full velocity from a nozzle, sort of a light rain sort of spray, if something is wrong under the hood this will shake it down pretty quick, and its cheap. If all that passes now you need to get serious. You will need to check the fuel pressure, bad fuel pressure means truck no run good. You see the PCM (Brains / computer) will always be trying to adjust the pulse width to the Injectors to correct for bad pressure. But if the pressure is all over the place then the PCM cant keep up and keep adjusting all the time. So you MUST verify constant steady fuel pressure according to the specs for your fuel pump in your truck. Once you do that, then your mind will be at ease, for everyone is going to want to replace your fuel pump, and it may need replacing, so you have to test it .
Good luck
darryl..