My car acts like it's ready to die out whenever I'm idling at a stoplight, etc. It runs fine when my foot is on the gas.

any thoughts on what could be causing this?

Details:
2004 Mazda 3s
91,000 miles

Thanks,
Dave

 

No CEL? Would suspect your evap purge solenoid is stuck open creating something like a vacuum leak. Purge valve sticking open is somewhat common on the 3. Try removing the line from the valve and make sure there is no vacuum when at an idle.
The purge solenoid is located just below and in front of the brake master cylinder resevoir. You will notice that just to the inside of the resevoir there are two metal pipes that come up from under bottom of car on the firewall. At the end of these pipe are fittings and then hard plastic hoses. One of the fittings is blue and the other red. Follow the plastic line with the red fitting and it will lead you right to the purge solenoid valve. Take this line off where it attaches to the valve. Small hose clamp will need to be removed first. With engine idling. Put your finger over the exposed port on the purge valve. You should not feel any vaccum here. If you do the valve is stuck open. You should notice idle improvement as well if you feel vacuum there and put your finger over it to stop the leak.

 

yea my 626 used to do the same thing. i had an oil leak and my spark plug would get dirty had to replace it all the time. the guy above me seems to know a lot, so i would go by wat he sez.