stuttering / almost stalling at idle

[mcG]

engine has been almost stalling on me when i come to a stop, especially when the lights and heat are both on, stereo is off. rpms will drop momentarily to under 500 for a second then kick back up. can this be my alternator?

its a 97 4.0sohc, 98k miles

 

[BradE.]

Clean or replace your idle air control valve.

 

[mcG]

how exactly do i find that / clean it?

 

[TPLYNCH]

Use the search button and type "how to clean IAC"

 

[eliii]

Will this cause the check engine light to come on? My problem is intermittent and is mostly when I back up and then shift from reverse to drive?

Clean or replace your idle air control valve.

 

[Mbrooks420]

Second the IAC valve. Doesn't typically throw a code, and is easy to get to. I'd try cleaning it first. An alternator won't cause the car to try and stall, typically.

 

[J_C]

Use a multimeter to measure your (charging system) battery voltage with the engine idling. It should be around 14.4V. Measure your battery voltage with everything off, should be around 12.6V [or least over 12.0V].

As far as the check engine light, use an OBDII code scanner and pull the codes. Autozone and some others will do that for free if you don't have a scan tool, though those only provide a code #, not live streaming data.

Ironically right now amazon has a great $15 price on a BAFX bluetooth connected scan tool but it will probably sell out within the next few hours:
https://www.amazon.com/gp/product/B005NLQAHS