I have a 2002 F150 with the 4.6L motor at 130K miles. Started rough idling yesterday. Will stall if in gear (like at a light), but will idle roughly in park.

Pep Boys pulled the codes: 0151, 0156, 0171, 0174. I cannot find any other posts with these four codes.

OK, so I'm seeing the codes as two pairs: The 015's and the 017's being matched together. Does anyone know which pair is the cause and which pair is the effect (if that's even correct)?

I checked the IAC by starting the truck and pulling the connector off... the idle immediately dropped. Snapping the connector back on resulted in the idle speeding back up (But, of course, still running roughly), so it looks like the IAC is fine.

I looked at the MAF... the little sensors on the wires don't look bad. The ones I have seen on YouTube videos look far worse. But, I'm planning on going out and getting some electronic cleaner and spraying them all the same.

I cannot find any vacuum leaks or hoses off/loose. What else can I look at if cleaning the MAF doesn't fix it?

Thanks

 

Keep looking, you still have a vacuum leak.

 

I have a 2002 F150 with 4.6L. It has 94,000 miles. I had to replace the IAC about 9 years ago. I recently notice a little misfiring so I replaced all spark plugs for the first time along with the coils. Immediately my truck started surging badly and would die sometimes when I stopped at a light or stop sign. It would keep running about 45 to 50 mph when I took my foot off the gas and when I hit the brake would surge when stopped from 2000 down to 500 rpm if it didn't die. These symptoms were lessened when I replace the IAC with a BWD 50619 part IAC which Auto Zone and PEP Boys say is for my engine but I had no codes showing and no check engine light coming on. I took the old IAC I had previous put on about 9 years ago and sprayed it out with carb cleaner and problem solved. Engine runs like new again!