I have a 98 f150 with a 4.2 v-6. It has started sputtering, don't know what else to call it, when it idles. Sometimes it will die, but it restarts with no problem. It doesn't do it all the time. If it put it in neutral when I stop it doesn't do it. It only does it in gear. Any ideas? I thought it might be the fuel filter or bad gas, maybe water in the tank. But wouldn't it do it in gear or neutral if it was any of those? Thanks for any help.

 

Is it time for a tune up? Idle too low?

 

I replaced the plugs and wires about 2 months ago. Also had a vacum leak and egrs done at that time also. It was misfiring and I had all that done. Unless there is another vacuum leak somewhere. It only started this a week or so ago. And it only does it after the engine has been running for a few hours. It doesn't do it when I start out for the day.

 

I was browsing forum and noticed your post. I am having the same exact problem! I have 99 f150 v6. I was going to replace the spark plugs and wires but I was told by a local garage to bring it in and run a diagnostic on it before I start exchanging parts. I was hoping to save some money and run it by an advance auto I hear they will do it for free.
I was also having some other minor issues and wanted to see if you were having them also; they may not be related but here they are: automatic locks on passenger door will function but not unlock all the way, the radio and odometer displays will work intermittently, and I have a check engine light on and abs light that have been on for probably 2 years even after I brought into a shop for repairs to the brakes and a cam timing sensor replaced. At a loss...

thanks
ron

 

I'm not having any of those problems. Other than the check engine light.

 

Try changing the fuel filter!!

 

i know i sound redundent, but this is sounds like O2 sensor to me...

 

RCS3, do a search for door lock actuators, and look at one of the most recent threads in the electrical section. Those will take care of the odometer and locks. Also, test your rear abs sensor.

 

If it was the o2 sensor wouldn't it do it all the time? It usually only does it after the truck has been running for several hours. That's what confuses me.

 

I was haveing the same problem and cleaned my I.A.C sensor and that seemed to clear it up.