My 97 f-150 4.2 v6 has a really rough idle. It is only rough at a stop or in neutral it doesn't idle rough in park. It takes a few seconds after i stop to start the rought idle. it also seems to lose strength when i go up steep hills. Sometimes at a stop after a few minutes of rough idleing it turns itsself completely off. Some one suggested that i change the pcv valve and that did not help. My converters seem okay. people have suggested 1000 different things and nothing seems to help the problem is getting worse anyone have any ideas?

 

Clean your iac or replace it. Also check your fuel pump

 

I just purchased one of those for my daughter recntly(well helped purchase)and haven't had that problem yet or any problems with it as a matter of fact.

How does it idle after a cold start compared to a warm one? I know when the O2 sensor's kick in @ about 800 degrees it effects idle. To determine it's your IAC it will idle rough after a cold start..

Your PCV valve could be malfunctioning as well. - (that's a cheap fix)

You might want to clean your MAF sensor first since it doesn't cost nothing and it could be the problem as well.

Here's how - http://www.fordf150.net/howto/clean-...low-sensor.php

IAC's are more expensive to fix but that is a common problem .. Try the easy and less expensive stuff first and you might get lucky..

The cheapest IAC's can be found on eBay @ the Rock Auto store..

Good Luck

 

I assume you have no check engine light?? If you clean the MAF disconnect both battery terminals for 15-30 minutes. Does it run allright while your driving it??

 

possible vacuum leak

 

thanks i'll try cleaning the maf sensor and the iac i've already replaced the pcv valve thought about the vacume leak have yet to check it though.Runs great while driving. thanks to all hopefully something will work!