Hi Dan - does it stumble for a short period and then kick back to normal
operation- or once it stumbles, the van doesn't let up and you can't
drive?  One thing to check if you haven't considered is to inspect your
ground connections in the engine bay to see everything is making good solid
contact.  The other thing the symptoms are reminiscent of is a bad O2
sensor - except it doesn't sound like you are noticing a rich fuel mixture
odor.

Hopefully you will get more scientific suggestions and instructions than
these.

Bruce

On Fri, Dec 2, 2022 at 11:35 AM Dan N <dn92610@gmail.com> wrote:

> hi all,
>
> I have an '88 tintop (298K miles) van with this problem. It starts fine,
> idles fine, revs up fine. But recently when it reaches operating
> temperature it stumbles, almost dying not willing to go up higher rpm. This
> happens with warm or cold outdoor temperatures.
> Things have been done a few days ago.
> - New dist. cap and rotor
> - NGK BP6ET are recent.
> - Throttle body switch checked fine
> - Idle screw on throttle body cleaned
> - A good fuel pressure regulator was swapped in.
> - Air filter checked.
> - AFM connection checked
> - No vacuum leak on any hose.
> - Idle control valve checked, working fine
>
> So what happened and what to do next...?
>
> Thank you for any help...
>
> dan
>