My money's on the coil, too. Especially if the problem only
occurs well after warm-up.

A failing main relay's symptoms tend to occur after running
awhile, then shutting off a few minutes, then re-starting.
It won't re-start until the car cools. The integrity of the
solder joints, with age, are temperature-dependent.

How old is the coil? Is the coil OEM?

Still, ever had the main relay replaced?

I replaced my 91 Civic's (176k miles) main relay c. 1999. No
problems since.

"Alan" > wrote
> wrote:
>> My girlfriend's '91 Civic has 150k+ miles on it and just
>> started acting
>> up. The car runs fine while driving around town, but once
>> we get it up
>> to high speeds it will just all of a sudden die the next
>> time we slow
>> down. Most of the time it starts right back up within a
>> minute or so,
>> but the last time it took about 20 minutes to start up
>> again.
>>
>> We took it to our regular mechanic, who took it out for a
>> test drive
>> and never experienced a problem. He said it might be the
>> fuel pump, but
>> that he wasn't sure.
>>
>> After reading through newsgroups on the subject, it seems
>> that maybe
>> the problem is the main relay switch. Any suggestions?
>
> My idea is that the coil is weak and the freeway driving
> is keeping it
> cool enough to work until there's more heat from local
> driving after
> the freeway driving.
>