488civ10

burhan24, any solution or update on your situation?

I appreciate the suggestions and help. As far as the IACV goes, as I understand your comment, it should be that once I give it gas, the problem should go away, correct? A stuck IACV would only be a problem at idle (erratic idle). Since you see problem at many throttle positions it must be elsewhere. It can only be fuel or spark. Obvious fuel issues are a bad tank of gas, intermittent fuel pump or pressure regulator, or clogged injectors. Spark issues are shorting wires to chassis, bad wires, bad coil, ecu issues.... Hard to prescribe anything very specific until you replicate the problem and diagnose it more. Could also be bad coolant temperture sensor which may be sending ECU wrong signal.

LOC guys/gals, i have a weird engine sputtering/ stalling problem that is intermittent (as in almost a year apart). it happened once last summer while my wife was driving it, then it went away. happened to me once in february 2010, but i put it into neutral, gave it some gas and the rpms roared and the problem was gone. my dad borrowed it last month, it sputtered again, with the rpms going from idling speed to almost stalling a few times, before it died completely. this problem was repeatable, and after he restarted the car, it did the same thing three times. so i had it flatbedded to my mechanic, and of course... he was not able to replicate the problem. yesterday, it was a pretty hot day, and with the a/c blowing and on my last stop of the day, getting ready to head home it finally happened again. when i step on the gas pedal, it doesn't do anything while it's doing the sputtering, stalling thing. i fully floored the pedal several times and still no response. i then popped open the hood to take a look at the engine as it was doing this (and tried slapping the IAC valve just in case), and saw the entire engine shaking and shuddering a lot. any idea what it might be? i searched the forums and read up on a ton of stuff, but nothing definitive, and no one usually posted follow-ups if/when the problem was solved. MAF, IAC, fuel pumps, coils, distributors? i had the distributor, cap, plugs and wires all changed in january (and took a problem-free road trip to san francisco, averaging 26mpg with the a/c on the whole time, going 80mph). being that i'm not very mechanically inclined past oil, trans/diff fluid changes, i'm worthless in the DIY department. i used to go to a former lexus tech who went independent, but his quality of work, service and honesty has gone to total crap. he said he couldn't figure my problem and couldn't get the problem to reappear. i don't believe he tried much, if at all given the mileage from the time of the flatbed tow to when i got the car back was exactly the same. speaking of which, i should check the MAF. i have a K&N, and i'm careful during the recharge/oil process. my former mechanic recharged it for me, and given his recent track record, perhaps he doused it with oil. anyway, any help/suggestions would be welcome. just want to have an educated stance before i call two local mechanics that have come highly recommended by two of my friends. cheers, 488civ10