Hey y'all, so I've got a 2003 f150 4.6 supercrew, yesterday I drove a few miles to get to my college and on the way home I notice I had a rough idle while at stop lights, then at one stop my truck stalled out, luckily I was able to start it right back up. Still had the same problem all yesterday and today. Seems like a vaccum leak but I can't find it, also there is some rattling near the drivers side front tire, don't know if that's related or not. Please help!!

 

You may want to take a look at the EGR valve to see if it's acting up.

 

Does your check engine light goes on? If it does I would try new ignition coils, I would check them no matter what.

 

Coil pack or spark plugs

 

If it was a vacuum hose you would have a high idle more than likely. If it is spark related you should get a flashing CEL while it is happening and it will store the cylinder # of the misfire. You should be able to hear if it is an injector misfire. Could just be something got loopy and your computer needs to be reset. Go to your local parts place and scan your codes even if you do not have a CEL on. After you do the scan reset the system with the scanner. Also if it is spark related it should show up as a miss at about 1500-2500 RPM with a decent load on the engine. Good luck let us know.

 

Thanks for all the help guys, looked a little more today and couldn't see anything else but I'm gonna take it to orielly tomorrow to check the code and see if that gives me some answers as well. Pretty sure it's not the plugs bc once I get up to around 1500 rpms it acts fine, it's only below there

 

most of the time a shorted coil won't throw a code

 

My neighbor had a similar problem and his turned out to be an injector that had came unplugged on #8

 

Update - I cleaned out my IAC valve earlier and that helped a bit but did not fix it, the next thing I am going to try is to clean the MAF and reset the system and see how that works out. Again thanks for all the suggestions, I am trying everything y'all are saying that I can afford haha

 

Finally fixed it!! After everything I tried just ended up being a huge vacuum leak in the PCV valve hose! Really excited I got it figured out!