Help needed with idle and acceleration

nascar99

New Member
Nov 18, 2005
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hello
heres the deal, i have a 2003 mustang gt with 27000 miles on it. about 4 months ago i started having problems with the car idling and stumbling on acceleration. when at idles it sometimes sits at 750 rpm, other times as low as 500, and other times up to 1000 but it never constant. now during acceleration (i have a 5 speed) i feels like it stumbles and has NO power before i get to 2500 rpm. when i take off from a stop i really have to get the rpm's up there or its just a dog. on deceleration coming from 3000 rpm's to 750 it feels like it chokes part way then opens up, and chokes some more. i've had it at the dealers twice, the first time the updated the ecu, and the second time they just did a carbon wash. i told the mechanic i thought it was the IAC valve, but he just blew me off. since having the problem i've added a 70mm t.b. and a Mac CAI, no help.
if anyone has any thoughts on this please let me know, any help is better than no help, thank you.
 
i thought it might be the IAC too, but the mechanic just blew me off like i didnt know what i was talking about. i do have a K&N filter, but all this started before i put any after market thing on my car.