Okay, here is another crappy idle thread. I haven't been able to find my exact problem. If there is a thread for this, sorry.

2003 Ranger 2wd with 208,000 miles, auto transmission, straight piped. This problem happens specifically in stop and go traffic when I am creeping along with my foot on the gas and I have to take it off rapidly. The RPM drops to the floor, and shudders like it is going to stall. The computer kicks in and prevents it from stalling. It has not thrown a code. I have also noticed that if I let it idle while in park, the car shakes, but the idle stays consistent (I'm not familiar with how bad engine mounts feel so, you would have to help me out on that one). I have a good reader at home that hasn't really given me anything that I can chase down specifically.

Realistically, I could probably "break" it and get a code, but I am hesitant to do it if there is a great likelihood of a mechanical issue over say a fueling, electrical/computer. I've yet to check the EGR valves/sensors, DPFE sensors, etc. That is probably where I will start. I haven't checked the fuel pressure, but I could this weekend (weather permitting).

A few things: It has a newer fuel pump (a little less than a year), air filter is changed with the seasons, IAC has been replaced in the last 1.5 years. I dump SeaFoam in the gas tank at the beginning of the month. Oil change was normal (I do it myself), everything looked good. Spark plugs and spark plug wires are older, but I did replace them in the last 2.5 years. Battery is less than a 1.5 years. I cleaned the terminals less than two months ago. Someone "tested" the compression and said it wasn't good. Keep in mind, they were a repair shop trying to get me to rebuild the motor. That was almost 3.5 years ago and the truck has been fine other than the above parts that have failed and were replaced. I had the transmission looked at, but I think that is most likely irrelevant for this thread.

Help a sister out.

Thanks.
-RogueRanger

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Rogue Ranger

2003 Ranger XLT

Full disclosure, I'm not an expert on cars, but I have wrestled with rough idle with my engine-swapped Miata on several occasions. The tricky thing about rough idle is that it can be caused by a multitude of things. It could be the following:

1. Bad plugs/wires (yours isn't very old but it is still possible).

2. The IACV is dirty (this doesn't take long to happen)

3. Air filter (probably not) or the intake itself could be dirty.

4. Throttle cable may need to be adjusted at idle.

What does your car typically idle at with the a/c off?

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Daily Driver: 2004 Hyundai Elantra

Toy: 1991 Mazda Miata 5 speed (engine swapped)

Workhorse: 1995 Ford Ranger 3.0 5 speed mods: Spark zinc drilled rotors and drums