deidrebtx

04 mazda3 sputtering in drive at stop lights. A/c on seems to make it worse. Seems to run fine as long as I'm not stopped. I have changed air filter, replaced spark plugs, put fuel injector cleaner thru and cleaned the MAF sensor! Has anyone else had this problem? If so, please HELP!

djs2571

no check engine light? Are you burning oil or loosing anything else like coolant?
Does it drive normal otherwise? any feeling of power loss? change in mileage?

deidrebtx

No CEL.. No oil burning. I did notice if I turn off the a/c it stops.

djs2571

I know there's an idle air control of some kind, though with electronic throttle I figured there wouldn't be a seperate solenoid or something like older vehicles that have a TPS and seperate automated systems.
There has to be a sensor that's going bad / wiring corrosion or something like that. Unless you go through looking at the signals (which some of can be seen with a scan tool) I think you'll have to wait to see when the CEL comes on and see what the code says.
The good news is that you can repeat the symptom sitting in your driveway - not a problem that only happens when you're at speed. So you may want to try wiggling some connectors to see if that changes anything.

deidrebtx

CEL P0128
doesn't sound like it has anything to do with problem I'm having.????

djs2571

Actually it could - when the engine is cold, it will run rich, and that happening for a while can dirty the plugs. The sensor is easy to find, on the battery side of the engine pointing rearwards... but i'd bet the thermostat is just stuck open, keeping the engine too cool.

Good luck fixing.