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.

-------------------------------------

Big x2.

'Curly'

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.

There are others. Start here, though.

Please confirm whether
-- OEM ignition wires and spark plugs were used
-- the air and fuel filters were replaced. If not, when were
they last replaced?
-- the battery is old. This is for the slow-to-catch
problem. Battery age in years and miles, please? What make
of battery is now installed? Do you have a multimeter to
check its voltage with the car off and on?

I have a 93 Accord EX with 158K miles, 5 speed manual, with an
intermittent problem.  It sometimes hesitates while accelerating at
low rpm. It happens when I shift to 2nd or from 2nd to 3rd or when
going around a corner in 3rd and then trying to accelerate.  It seems
to go away when the rpms get higher.

The main relay was replaced in June 06 when the car would not start
(crank but not start).  This hesitation/jerking/stumbling problem is
recent.  Last week I had a tune-up at Honda dealer - spark plugs were
replaced and timing, belts, hoses & filters were checked.  The fuel
relay (Relay RZ 39400-SM4) was replaced.  It did not fix the problem.

Also, sometimes when I start the car it sounds like it isn't going to
catch but then does.  Again, it doesn't do this all the time.

Any ideas on how to fix this problem without replacing everything in
the car?

Thank you for any advice.