"motsco_" <motsco_@interbaun.com> wrote
> Elle wrote:
>> I would start by checking the coolant in the cooling
>> system reservoir. If it's not between the max and min
>> lines, then fill to the max line.
>>
>> Certain engine control sensors must be immersed in
>> coolant to work properly. If the coolant is at all low,
>> they may not be immersed. The sensors then send the wrong
>> signal to the fuel and air control systems.
>>
>> Especially if the coolant was recently replaced, do this.
>> It costs little and is a common cause of the problem you
>> describe.
>>
> -------------------------------------
>
> Big x2.

I happened to have changed my 91 Civic's coolant on Friday
but was a tad short of distilled water to mix with my
Havoline (orange anti-freeze), and so did not quite top off
the system per the manual. After letting the fan come on
twice, it looked like it had enough. Saturday morning
driving down the highway I get the hesitation and stumbling.
Then the Check Engine Light comes on. I figure it's gotta be
the coolant. Temperature gage looks fine. I got to where I
was going and checked. The reservoir was well below minimum.
Still having no distilled water, I added 2/3 cup of pure
Havoline to the reservoir. A couple hours after the car was
parked (and I attended to my reason for the trip, an
errand), I drove a few miles. The CEL did not recur for this
short, low speed trip. At the store I bought some distilled
water and added 2/3 cup to the reservoir (whose level had
not changed during the short trip). I brought the reservoir
back up to max, then drove the car home. It was holding
steady at about max. I let the car cool and topped off the
radiator. All seems fine now.

Fully supporting your claim of many a time here. :-)

A few years back, I had a related problem with a lack of
coolant, but this time, it was the EACV that was starved.
Plus, this instance a few years ago did not occur until at
least several weeks after my coolant change.