2002 scab 5.4
Threw these codes this morning. I know when these codes come up together it usually means a vacuum leak so I will check that when I get home but my question is if that checks out fine where should I go from there? Thanks!

 

I have had those for awhile gonna attempt to fix this weekend also have the anti theft code all of a sudden as well

 

Bump

 

I replaced the line on the back of the throttle body as it was dry rotting. Checked all other vaccum lines and they all check out fine. Reset the codes and they came back up. Not sure where to go from here. Could it be a COP?

 

Smoke test it if you have one could be another leak

 

I have the same codes. I'm still trying to find the problem. So far I've cleaned the MAF and smoke tested it. I will let you know when I find the problem.

These are some of the things I've read could be causing the codes.

Dirty or faulty MAF.
Vacuum leak, usually from the line you already replaced or from the manifold gasket.
Clogged or faulty fuel injectors.

I've addressed each of those issues. After cleaning my injectors and reinstalling them, my truck started and ran a minute or two and then died, I started it up a few more times and it would immediately die each time, now it won't even start. I'm thinking maybe it's just flooded, idk.

 

Replace pcv, clean the MAF with appropriate cleaner, check all vacuum connections.

 

Here was my problem with my 4.2L at 175,000 miles: http://nicholasfluhart.com/2012/10/0...ifold-gaskets/. Obviously, I checked everything that was already mentioned before doing this. Not sure if this is as common (or whether it is uncommon) with the 5.4L as it is with the 4.2L engine. Fuel economy went from 13 MPG to 17.5 MPG after.

 

I had this same codes on my 4.2L '03, and it turned out to be clogged EGR (I think) ports in the lower intake. After taking off the upper intake to check those for bad/leaking gaskets like themerc suggested, I found that three of the tiny ports were plugged solid. I opened them with a small drill bit (hand spun) and then some carb cleaner on Q-tips. That cleared the error right up (although I saw no signs of leaking upper air gaskets, I did replace those, so I might have fixed a leak there as well).

 

I cleaned the MAF real good. It wasn't to bad but could use a cleaning. I reset the codes again so we will see if they come up. Thanks for all the help guys. This is why I'm a part of this forum