Last year was a pretty light winter, but when it did snow I had an issue with rough idle, and stuttering while accelerating. It only happened the 2 days it was really cold and then it went away. I thought it might have been condensation in the tank from the freezing.

This past week, this year's snow came and so did the problem.

Starts fine, and runs fine for about 15 mins. Then it starts to get rough.

Runs rough at a stop while in Drive, smooths out if stopped and I put it in neutral.

Stutters at acceleration from a stop and then seems to smooth out as driving, but if I take my foot off the accelerator and then give it gas it stutters again.

Freeway driving is hit and miss. It will smooth out over 65. Between 50-65 it is rough when applying the acclerator.

Service engine light will sometimes flash when this happening.

I have searched and found info on everything from Rear 02 sensor, to IAC, to coils. Was hoping someone here can provide some insight so I don't throw money at it for parts that are not needed.

2001, 5.4, 4x4, just over 80k. Would like to fix it myself.

 

Start with the cheap and easy, clean the MAF, put some water remover in the fuel tank and change the fuel filter. Then go with the spark plugs.

 

You have a cop on its way out. You can start your truck and let it idle....then unplug each cop(coil over plug) ONE at a time.As you unplug one listen and feel for a change in the way it idles/runs,If there is no change then that is more than likely the bad cop (coil over plug) Take the one small bolt out and pull straight up and off the plug.I bet you will find rust on the coil like conductor thats inside the rubber boot.Thats what causes these cop's to fail. Go to autozone or napa and get a replacement and put back in.

 

If the light came on save yourself some grief and get the codes read. It will go along way in helping diagnose the problem. Is your vehicle well maintained?

 

^^^ like he said if light flashed then you have code in the memory... stop at an autoparts store that has a code reader for you to borrow and check it out

 

Cleaned the MAF, and water remover, and injector cleaner. No problems since then. In fact, since the MAF was cleaned it has been running better. Seems to have a little more response when accelerating.

Thanks all for the info.

 

Problem is back. I got a CEL and code P0306. Replaced COP and plug on #6. Still have same problem. The plug was pretty bad looking when I pulled it. Wondering if I should go the route of replacing the injector? Any help is appreciated.

 

It is fixed. In my haste to see if replacing the plug and COP worked I forgot one very important thing...I did not connect the plug to the new COP

 

Did you have to pull the fuel rail to get that cop out? Mine look too close to pull with the fuel rail in the way.

 

Ah yes, the ever present ID10T problem...

I did something similar when I put an aluminum intake and 4bbl carb on my Cougar. Forgot a 1/2" pipe plug in the intake and it took me forever to figure out where the damn massive vacuum leak was.