So interesting sequence of events leading to a fairly significant issue.

It is worth noting that prior to all this, the car ran perfectly fine.
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​​​​​​So I took it upon myself to change the trans fluid and filter out in my 97 ls400. Bit of a pain to deal w Toyotas fipg but managed without damaging anything (as far as I know).

After I finished refilling the transmission w T-4, I start the car, it fires right up, and I immediately hear a loud wooshing sound so I shut it off. I realised that since I still don't have my brake booster attached that the vent tube was sucking air so I reattached it and went to start the car. This time, it started up but then died instantly after. Upon subsequent starts I discovered that if I manually give it gas, it remains going, but if I take my foot off the pedal, it's gone.

Anyone have any thoughts or ideas on what it could be?

Other things worth noting, my battery is currently dead so every time I start it, it's with a jumper. No obvious fuses are blown. I tried resetting the Ecu 3 times. And no master cyl/brake booster are installed except for to plug the vacuum leak.

Thanks

 

these cars are notorious for running funny if the battery is not operating with a good charge, there's a whole lot of electrical stuff that doesn't like a drained battery not sure if that's it or not but could be

 

Alright, thanks for the insight. It seems like it could be electrical as I haven't touched any of the physical components, guess it wouldn't hurt to start there

 

I concur about the battery, not a novice even with these cars but the battery threw a bunch of codes for me before and once i replaced it, everything was normal.

 

Well the battery is only a year or so old so probably doesn't need replacing, only died since I forgot to disconnect it while doing a bunch of work and the lights drained it out, but I will charge it up and then update whether or not it solved my problems

 

Well an update, the battery was so dead that the AutoZone tester didn't even recognize it as a battery and it couldn't be charged at all. Got a new one and it runs and idles just like it used to! Not exactly a cheap fix but compared to an $800 IAC I'll take it.

 

the car's ECU needs a good battery to know where to set the idle control valve, which was likely reset when the battery drained to dead.
all the idle maps, etc will now have to be relearned as you drive the car with the new battery.