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I have been dealing with this issue for a while now.

When I am driving if I am doing like 3000rpms and pull the clutch in and let off the gas the engine rpms will not stop going down at 650. It heads right to 0.

If I rev the engine while idling it will go down to 300 or so then back up and sometimes hunt for idle.

The dealership said it could be a TPS but I just put a new one in. I adjusted it with an ohm meter initialy and just tried moving it back and forth while the engine was running to see if it would make a differance. It didnt seem to.

I asked the dealer if the Idle controll valves go bad in these things but they said not usually. If I pinch the vaccume hose going to the ICV the engine dies so I assume it is working.

Anyone run into this issue?
 

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Little vacumn thingy

I think your problem may be the little vacumn diaphram device right below the throttle linkeage ( opposite your tps) Its supposed to dampen the last bit of traval when you take your foot off the gas. (The short hose on it goes to a piece of cotton filter to stop dirt from getting it. Do not hook it up to vacumn lines) There is a small jam nut and flat head screw your can turn in to contact that device sooner. Sometimes the diaphram goes bad.

You may also have a vacumn leak. Those can be hard to find sometimes.
 

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The diaphragm device is called a dashpot. The dashpot prevents the throttle plate from closing abruptly during the last 1/8th of an inch or so of movement during deceleration before the throttle shaft linkage contacts the throttle stop screw on the TB. This helps reduce CO and Nox emissions during deceleration. I would double check your throttle stop screw setting and your TPS adjustment per the procedure in the TSRM. The TPS can be a little tricky to adjust and obtain the proper setting.
 

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searched through some threads and came across this old one...

i have this exact problem, but with my 7mgte. could the dashpot be the culprit or the icv? Could a lazy startup be relevant to this issue?

also, could a aftermarket X02 bov cause this? seems like the bov sounds off fairly easily under normal acceleration. ask any questions to narrow down what it could be...
 

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I'd bet most dashpots are pretty much non-functional at this point and it hasn't caused a rash of issues such as you describe. Don't think a stuck dashpot would cause any running issues at all that the average driver would notice. After you figure out what is really causing the problem and fix that, then would be the time to try to free up the dashpot with a little WD40 or teflon oil or such and adjust. Besides, they are class F anyway.
 

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completely forgot about this thread...

the bov is recirculated. i replaced it with a bosch 110 and it stopped turning off after when put in neutral after acceleration. but it still takes about 5-8 cranks before it slowly starts up. after it warms up, it fires up in one shot... could it be the icv? tps? i should get a video of how it starts up so you guys can hear and see it idle....
 
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