Ford 2003 F-150 idles rough and then dies.

LTMAJ

MEMBER
2003 FORD F-150
4.6L
V8
4WD
AUTOMATIC
17,200 MILES

I have a Ford 2003 F150 4wd v8 4.6l automatic transmission that the check engine light came on about a week ago. It idles very rough, the RPM's will jump up to 1500 then drop to 500. Every so often it just die at a stop light or stop sigh. This happens only when I am stopped. When I am driving everything is fine. I took it up to have the codes read and it said that he MAF was bad, so I changes that. I drove good for a day the went right back to the same problems. I went back up to have the codes reread and they said the MAF was still bad. I told them I had just changed it. Their response was to drive on it awhile. The problem continued, I asked some friends they recommended I change the IAC valve so I did. Problem continues, I took it to another place to have the codes read and they said the MAF is still bad along with the O2 sensor is bad. I told him I had replace MAF. He thought the O2 sensor is the problem, but then said that would cause your truck to die. I don't hear a vacuum leak anywhere. I am not sure where to look next. Thanks for your Help

1 Reply

HMAC300

MECHANIC
48,601 POSTS

If the code is not erased after the part is replaced and that sounds like it here then the code won't go away. Check your duct work from maf to throttle and see if there are any holes in it also all the grommets on engine same thing as it will set that code. Then erase the codes and start over. Also clean throttle plate on both sides and iac hole with choke cleaner.