I'd vote Temp I and II sensors, or the connections thereof. Disconnect the
O2 sensor just to see if there is any change.

Jim

On Fri, Dec 2, 2022 at 1:35 PM 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
>