Wow, I am at a loss where to start. I have a 2002 3.0 V6 non-flex fuel Auto Ranger.
Here is the issue, I will try to keep it short, but it probably wont be. Any help is appreciated.
The truck, when I come to a stop and idle, will drop down to 500-450rpm and if in put into park, even lower and usually die. The idle is extremely rough and feels like it is going to poop out. No difference is noticed with the A/C on or off, as well as the stereo. Also, the oil gauge will flicker like crazy occasionally at idle. The door sensor is out also if that matters.
When I bought it, it idled rough, but at the appropriate rpms (650-750 in drive) but it was missing. The plugs in the truck were replaced, solving the missed cylinders. Fuel filter was also replaced. The truck was idleling smooth and drove fine. The truck always started right up.
A day maybe two after changing the plugs, I started noticing the low rough idle. As well the battery gauge would fluctuate up and down (maybe a 1/4" of movement). However, as long as I was driving or giving it gas everything was stable. That night my truck did not start, I had to have it jumped. Then it ran fine.
In the morning it started right up, and hasnt had a problem starting. However, this idling problem started happening, but it was off and on. It would be fine one day, but the next day it would do it. It has since become consistent for the most part.
The battery in the truck was old (2007) and had acid on the terminals so I just replaced it with an Optima Red Top and the fluctuation seems to be gone (still moves a tiny tiny amount I think).
It seems to always be fine when I first start the truck, but then slowly go down to that 500rpm at idle and get rough, and I feel like it goes lower and lower the longer I am at a light. The Oil Guage will also flicker occasionally (which is too often).
Though the truck will drive fine, I do notice a change in sound, when I dont have the low idle it sounds more "windy" Kinda like a big fan (think its just intake noise, not familar with the engine) but with the low idle problem it sounds like there is no "wind" but lower and more "growly" and have that engine cam noise which sound more normal to me. Not sure which is the correct sound? And Im not a hundred percent that this is even a problem.
In addition, The engine temperature is always good and stable, the truck runs fine. Oil is clean and level is good. Air filter is good.
The only things done to the truck is New plugs, Optima Red Top, New fuel filter, and a HID kit (ebay, could be a problem?)
One thing I saw was a snipped small red (apprears to be a ground) wire just left of the fuse box bolted down under a wierd plastic can lookin thing (zero idea what it is). I will post a picture later today.
I thought I would start with the basics, clean the MAF, IAC, replace the PCV. change my spark wires as well. I havent done this stuff yet (no much time in my life.) But I was hoping someone had this problem or could point me to a good starting point if the above doesnt solve this. I know it could be anything from the computer to possibly a vaccum leak. Looking for a similar experience or some Ranger expert, hope someone can help.
Thank you very much for taking the time to read this long post and help out.