Alright, so I have a 1992 4Runner V6 3.0L with 249K on a twice over rebuilt motor. I've had her since 2009, never had any major problems besides the shady engine rebuild and that it overheats if it runs with a thermostat, but last summer and now currently, if I drive for longer than 15 minutes, whenever I come to a stop, she idles so low that it'll die unless I throw it in neutral and keep the RPMs up where they should be. Mind you, this only happens when its over 70 degrees outside. Has zero problems if the outside temperature is below 70. Needless to say, I am baffled. I've asked multiple people and have been told it could be fuel lines, something getting too hot, a bad sensor, etc. Does anyone have any idea why my truck is being so tempermental?

 

does it still do it when it warms up if the temp is below 70? sounds like something is expanding as the engine warms up. possibly vacuum leak? not sure though. i know thats a common culprit for idling problems.

 

No, it doesn't do it when it warms up as long as it's not hot outside. Someone else I talked to said it might be a vacuum leak too so maybe I'll look into that. I just know I'm getting really irritated driving in traffic and my truck dying. Like, I hate to say it but I'm ready for summer to be over just so my rig will run normal.

 

test your vafm. the intake air temp sensor may have let go... usually not a major problem, but can cause issues

Obviously... vacuum leaks are a bad thing.....

Other things that come to mind...

cold start injector, or sensor...

engine control temp sensor, aka ect sensor,

bad o2 sensor...

search up the fsm (factory service manual) and start testing!