RPM's randomly shooting up then drops to normal while driving. - MustangForums.com

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Old 08-29-2014, 03:11 PM   #1
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Location: AZ
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Default RPM's randomly shooting up then drops to normal while driving.

I'm not a very car savey guy. I have a 2000 V6 Mustang that's more or less run great for years. was my first car and have been driving it for the past 14 years and only just a month ago hot 100k miles. recently Ive been having a ton of issues though. the latest repair was the fuel pump. the original was dying and my car would constantly stall out as the pump overheated. I finally had a new pump installed and the car ran normal for about a week then suddenly I had a new problem. It feel like it usually takes a second for the engine to fire up after starting the ignition if its been sitting for a day or 2. it no longer stalls on me but as I drive it feels like i'm hitting a wall of jelly. the RPM's shoot up from about 1.5k to 3k rpm and hangs there for a few seconds before dropping back. It randomly does this as I drive sometimes frequently and sometimes not. my transmission has a leak and I suspected a bad tranny but the fluid seems fine, not burnt or anything and I replace it as needed. I do have a check engine engine light on and when I had it read they gave me a giant list of what it could be (all fuel system related). I've changed the oil, fuel filter and spark plugs just prior to the new fuel pump. I know my best bet is to take it to a shop but money is very very tight right now so I'm wondering if anyone here can possibly point me to any simple issues it may be. I see a lot on the net about RPM's dropping and cars stalling out with fuel system issues but not much about the issue I'm having.
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Old 08-30-2014, 09:09 AM   #2
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It would be most helpful if you had the codes read and listed the particular codes that are popping up. This would at least give us an idea of where to start .
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Old 08-30-2014, 10:25 AM   #3
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Sounds like maybe a faulty IAC motor (Idle Air Control)

As dawson has said, any check engine lights?
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