I am a new member, but, I have been reading your forums for a while. I have looked, I have not found a post that truly hits on the issue I am having - I really hope one of the members here can offer some advice.

I own a 2009 Mustang - V6 - 4.0L vin N 245ci - MFI GAS SOHC, 102,000 miles.

Roughly two months ago I was sitting at a stop light, I heard ( felt) my cars idle drop and it felt like it was going to die/ stall. As soon as I took off from the light, nothing else. It almost felt like the transmission slipped - if that makes sense. I took it to a transmission place - it got a thumbs, the manager said my transmission was in perfect operating condition. He said I might want to have the throttle body checked out - due to the description I gave him of my issue. I had the plugs changed ( wires looked good), oil changed, and throttle body cleaned ( it was very dirty). The car ran better - smooth idle at 750 rpm in idle. Today - the same thing happened. Stopped at a light - car idle dropped. This time after the rough idle - it surged to about 1500 rpm - light changed, I started to move forward - it happened twice as I was driving ( Idle surging). I have driven it twice since then - nothing. It runs perfectly. I took it to Autozone both times - No codes are showing up.

What am I missing? Any ideas?

Thanks in advance - I have this car paid off.. I would really love to keep it in excellent running condition for years to come.

 

HMMM, when you put the pedal to the metal, everything OK?

 

Yes - It seems to be running fine. Same amount of pick up, feels like the same amount of power. I really thought today it was going to stall when I took off from the light. It felt like a surging in the engine ( RPM's went up)and then a choking/ bogging down feeling.

How sad is it that I was hoping for a code at Autozone?!

 

my 4.0 does it every now and then.

 

My 2014 3.7L did that last week. It was very strange. It has only done that once.........so far.

 

I have the same issue, sounds like its about to die; but it just drops in rpms. I'm thinking maybe the tune has something to do with it. I'm sure a bbk throttle body would clear things up

 

I wonder if fuel injector or carbon related?? I use Tier 1 and add a bottle of Techron every 10K, when I rotate tires. Mine is not a DI engine, but would be more important if it was.

Did any of you find the problem and fix?

 

Mine did it again this week. Tried to take off from a stop and it lost power for a few seconds then came back.

 

Hows the condition of your charging system? have you replaced the battery or alternator or are they still original. a drop in voltage would cause this issue and the alternators are known for going bad and causing weird gremlins. check your sjb connections in the pass kickpanel and make sure it hasn't gotten wet/corroded. good luck

 

I should have been clearer in my description. It did not lose electrical power, the engine just stumbled and would not make any power. All other electrical systems were fine.