Engine idle ect...help?plz

[JPstealth]

I just recently bought my 1st mustang. a 2000 GT with 59k miles. i love the car, i have always been a Chevy guy, this is my 1st ford anything. I am no mechanic by any means but dabble here and there when i can.

Anyways, heres my problem. The car won't idle, never stalls but it drops between 500-1000 rpms. I was thinking IAC? The car is also backfiring when I'm just sitting there or coasting. It also hesitates under heavy throttle. The service engine light came on, I replaced all the plugs, and it led to a coil i changed both and it went away and car felt a little better. A day later its back on still giving me issues, haven't had the code read yet, but any ideas?

Thanks

 

[DBMSTNG]

auto GT's idle at around 600rpm. i believe the 5spds idle around 900rpm.

you can remove the IAC and clean it with brake cleaner. if that doesn't solve the problem, i'd start looking at the injectors as the problem. they may be clogged. try some injector cleaner or seafoam. does the car have a K&N air filter? if so, some of the oil may have gotten on the maf. if so, you'll need to clean it carefully. i hope this helps.

 

[JPstealth]

i checked out the service light today and came up with the IAC, misfire in cyl #4 and running to lean. i picked up a new IAC and going to throw it in tomorrow. the misfire.. i replaced the coil and plugs and it went away but now its back in the same cyl? maybe the wires.

injector cleaning definitely worth a shot before i start messing with the timing.

 

[2000fordstanggt]

i checked out the service light today and came up with the IAC, misfire in cyl #4 and running to lean. i picked up a new IAC and going to throw it in tomorrow. the misfire.. i replaced the coil and plugs and it went away but now its back in the same cyl? maybe the wires.

injector cleaning definitely worth a shot before i start messing with the timing.

if you put in a new plug and cop then i would check your injector next. if you use any injector cleaner i would only use lucas.

 

[Turbo92PGT]

I would bet that if it does have a K&N that the mass air got dirty. Just like DMBSTNG said. That will make it run like ****.

 

[2000fordstanggt]

the autos and 5 speeds idle at a different rpm?