On Fri, 15 May 2015 13:29:55 -0700, The Real Bev
> wrote:

>On 04/21/2015 04:20 PM, The Real Bev wrote:
>> On 04/21/2015 03:18 PM, Bill Vanek wrote:
>>> On Tue, 21 Apr 2015 14:37:57 -0700, The Real Bev
>>> > wrote:
>>>
>>>>Two data points:
>>>>
>>>>(1) On the freeway, at roughly 55 mph, I gunned the engine. Passenger
>>>>reported it went up to 3K before I backed off, at which point it dropped
>>>>normally. Just a test...
>>>>
>>>>(2) Leaving a parking lot, with my foot on the brake, the involuntary
>>>>acceleration started. I immediately shifted to neutral and watched the
>>>>rpm rise to 2700 before I tapped the accelerator, bringing it back to
>>>>normal.
>>>
>>> 2700 is about the limit of the ISC motor. The contact switches in
>>> those can go bad, and cause that (it doesn't know it's in contact with
>>> the throttle lever), or the ECM. I would think that if it was the ECM,
>>> it would happen more often, but the tap test might help, too.
>>
>> *I* backed off; the rpm was still rising in both cases.
>>
>>> Regarding the ISC, the plunger is spring loaded, and you can feel the
>>> contact switch with slight pressure - it will move very slightly in
>>> and out. That switch could be bad, but another cause is weak throttle
>>> return springs that can't push the plunger in enough to close the
>>> contacts, or a sticking throttle. In fact, either of those two
>>> problems can cause what might feel like unintended acceleration.
>>
>> Not "feel like." IS!
>>
>>> If this happens again, you can always put it in park, open the hood,
>>> and look to see if the ISC is fully extended, holding the throttle
>>> open. If it is, push the plunger in, and if it retracts then, it's
>>> almost for sure a bad ISC motor, unless you can see that the throttle
>>> lever is clearly not pushing against that plunger. If that's the case,
>>> it's either the springs, or a binding throttle shaft, or throttle
>>> plates.
>>
>> ...for extremely rare values of 'always'.
>>
>> Next week I go back to the mech with a lot of questions...
>
>The bad news, which was ameliorated before by replacing the return
>spring with a heavier one: bad bushings in the throttle body, allowing
>sticking, slop, etc. No replacement possible, unless maybe from a
>wreck.

Yes, that was a common problem, and years ago. I don't know if I
remembered to mention that one, though.

There might be some specialty shops that can replace the bushings, or
there might be aftermarket throttle bodies somewhere. At some point,
though, it's not worth the expense.