Car Starting Issues...

[Kane]

99 Mustang GT, about 59K miles. I've noticed that recently I need to let the car warm up a bit before I take off, or it will bog and hesitate when I get on the gas...but the car has been starting. Now, when I start the car after it's been sitting several hours, it bogs and acts like it wants to cut off. I'll finally get it to smooth out with a little gas. Car runs perfectly fine. The weather has been a little cooler, but I've never had issues starting the car before. Input?

 

[Red2000GT]

1st guess-O2 sensor or sensors.
2nd guess-fuel pump on the way out

 

[COramprat]

O2 sensors would throw a code.

Check the IAC (idle air control valve). Could be clogged and causing your problem.

 

[Kane]

I had thought oxygen sensors, but there are no codes. I'll check the IAC. Thanks!

 

[Mustanggt108]

i dont think it would be the fuel pump because after the car gets warm , it runs perfectly he said.My guess is the IAC as well , it might need some cleaning.

 

[peterman1551]

I had thought oxygen sensors, but there are no codes. I'll check the IAC. Thanks!

 

[peterman1551]

I had the same issues at about 70,000 with my 99 GT. Sounds like it is definitely the IAC. Some say you can remove it and spray it down good with carb cleaner to fix the problem, however, there are internal parts in it that carb cleaner will not clean as I found out. The problem came back quickly. I would replace entirely. Expect that if you keep the car, and even if you properly maintain it, you will need to replace it again at around 100,000 to 120,000. I need to replace mine again and I have 132,000 on it.

 

[Kane]

Ok, it was a little warmer here in Indy today, and the car started without ANY problems. Started right up when I left work later on as well. Temperature related problem? I haven't cleaned/replaced the IAC yet.

 

[COramprat]

It is an intermittant problem that will get steadily worse. I let mine go about a year before I got annoyed enough to replace it.