22R - Hesitation At Steady Speed

For a few months, my '88 Toyota Pickup with a 22R engine and 4-speed
trans, has had a slight hesitation above about 50 MPH in high gear. The
same hesitation is there at lower speeds in lower gears, which leads me
to believe it's an ignition problem. If I'm going up a slight hill,
there's no hesitation, so it sounds like it's related to vacuum. Is it
possible there's a broken wire in the distributor that momentarily
looses connection at a certain vacuum level?

This hasn't been a real problem since I drive less than 100 miles per
week and seldom drive at freeway speeds.

I'm thinking of replacing the distributor, to the tune of around $160.00
for parts.

I have a mandatory smog test coming up at the end of October, so am
thinking I'll see how it goes. If it fails, I'll replace the distributor
and have it retested.

I had thought, at first, that it may be fuel related, but have pretty
much ruled that out since it's fine at wider throttle openings. It has a
fairly new fuel pump and the filter has been replaced. It ran fine after
those changes, and started the hesitation a few months later.

Any help would be appreciated...
--
Tom - Vista, CA

I solved some performance issues when I reattached a loose hose on the
EGR system and washed the dirty filters in the EGR modulator in
dishwashing detergent and let the filters dry. My truck has only
275,000 miles on it and is a 1987. It had a few skips about 175,000
miles ago but none since.

If your distributor is like mine there is no vaccum advance in it. I
think you are throwing good money away. I would start with cleaning
the EGR system.

On Sun, 28 Sep 2008 07:19:46 -0700, TOM <tom.RemoveThis@catz.org> wrote:

>For a few months, my '88 Toyota Pickup with a 22R engine and 4-speed
>trans, has had a slight hesitation above about 50 MPH in high gear. The
>same hesitation is there at lower speeds in lower gears, which leads me
>to believe it's an ignition problem. If I'm going up a slight hill,
>there's no hesitation, so it sounds like it's related to vacuum. Is it
>possible there's a broken wire in the distributor that momentarily
>looses connection at a certain vacuum level?
>
>This hasn't been a real problem since I drive less than 100 miles per
>week and seldom drive at freeway speeds.
>
>I'm thinking of replacing the distributor, to the tune of around $160.00
>for parts.
>
>I have a mandatory smog test coming up at the end of October, so am
>thinking I'll see how it goes. If it fails, I'll replace the distributor
>and have it retested.
>
>I had thought, at first, that it may be fuel related, but have pretty
>much ruled that out since it's fine at wider throttle openings. It has a
>fairly new fuel pump and the filter has been replaced. It ran fine after
>those changes, and started the hesitation a few months later.
>
>Any help would be appreciated...