Question about idle after cleaning throttle body/MAF
 

Just bought the car a few months ago. First mustang so i dont have much knowledge about them; hopefully someone can help me out.

Anyways, i took intake and throttle body completely out to clean both. I used CRC throttle body cleaner for the throttle and CRC MAF cleaner for the sensor.

Car has 50,000 miles and is a manual.

The only thing i have noticed that seems off to me ( i dont remember it doing this before i cleaned it) and maybe this is just normal but when im coming up to a red light (generally going about 40) and i put the car into neutral (clutch peddle in shifter in neutral) the car goes to idle 750 like it always has.

Problem is when i take my foot off the clutch (shifter still in neutral) peddle the rpms go to about 1000-1100 and then jump up to anywhere from 1500-2000 and dosent go back to 750 until i come to a complete stop. Not gradually either, most of the time it stays at about 1500-1750 until right before i stop and it drops quickly.

I have the same issue and it typically happens when I am about to come to a stop and am shifting into neutral. This has been happening off and on for years, with no real issues.

I also clean the throttle body/Mass Air Sensor, which helps a little bit. Try disconnecting your negative battery for about 30 - 40 minutes, reconnect and drive the car around a full cycle and see if that helps.

Good to know im not the only one with this problem. So this is something out of the ordinary? Did you have the problem before you cleaned anything?

Iv disconnected the battery twice but only for about 15 mins so ill try that. Thanks!

Mine does the same thing with the high idle, I don't think it's a problem however, it would be a problem if it didn't drop.

Yes, I had the problem before I cleaned the throttle Body and MAF sensor. The reason I cleaned up was hoping it would resolve the issue, which it didn't, but it did reduce the symptoms some. As long as the the idle goes back down, I am not too worried about it.

I'm pretty sure this is normal for these cars, I hear about this all the time and yes, mine does it as well.

Well i tried disconnecting the battery and driving for a while and the problems still there but if everyone says its normal im not gonna worry about it. Appreciate the help guys

Same thing happens to mine. 2006 mustang gt auto. Sometimes when I don't let it warm up after starting it, it surges coming to a stop and sometimes stalls out. Which is weird cause i have an automatic. It especially happens when I have the A/C on. I'm gonna clean the MAF sensor and throttle body tomorrow when i have time.