06 Mustang GT [automatic] stuttering when downshifting to go faster

Hey guys, I drive an automatic 06 mustang gt convertible premium. basically stock. im not quite sure if it is a specific gear that this issue takes place in but im going to try to give as much info as i can. When im in lets say 3rd gear and i press down on my pedal so the gt downshifts to a lower gear but higher rpm, my rpms stutter or freeze in between 2000 and 3000. It doesnt accelerate and if i let go of the gas pedal then tap it again it downshifts no problem. sometimes it takes a few tries. I wasnt able to find a specific solution on the internet but binge watched many tutorials and videos talking about what the problem could be. I plan on replacing the spark plugs and possibly doing a throtle body cleanup. If anyone could tell me what is causing this problem Thnks. Also when im below 5 mph and i lightly tap on the gas (for example if I am in a store parking lot and just want to apply a little bit of pressure to move forward) I hear this disgusting crunching noise. The car doesnt drive differently during this but it is a horrible sound like someone just shot a bullet through the front of my engine. it runs perfect after I warm it up but I am mainly concerned about the first part rather than the last part. If you have any questions for me to help you better understand my issue feel free to ask. I am open to all suggestions, comments, or concerns… :slight_smile:
edit: i got it read a few days ago and the code is: engine running too lean block 1

I’m no expert but this sounds like a transmission issue. There are a couple of really smart folks here in the community who can probably add more clarity to the diagnosis.


How many miles on it? Is the check engine light on?

117k . my fuel gauge reads it half full when empty and when i fill it up it says check engune but goes away. and comes and goes

Have it read at Autozone or another parts place for free. If it showed the light, it will store a code. Post it here and we’ll try and help. It should be in the form P1234. The code says where to look, without it we are a bit in the dark.

Pay little attention to what the counter person tells you. They are not mechanics.

There was a TSB about fuel pumps on that model but I would guess that’s already been corrected(?) And it’s remotely possible the “disgusting crunching noise” is a loose heat shield but that’s simply a guess.

Engine running too lean block 1

What was the actual code number Pxxxx
There are 30 some codes that say bank 1 running lean, and they all mean something different.


The code in the form P1234 like I asked, please. As @It_s_Me points out, there is more than one lean code.


I dont have that, ill have to get re read at a auto shop

How is the transmission fluid? Like both the color and the fluid level? Has the fluid ever been changed?