Best I can think of: turn the heat to max and bleed coolant. Remove the
battery for a minute to reset ECU.

> My 88 Honda Accord Lxi with 200K plus milage started rev'ing up and down
> after warming up. I thought maybe the vacuum adv. on the distributor
> might be bad, but verifing timing (pulling hoses and blocking/ chk
> timing) all are alright (car does not rev up and dwn when I do this).
> But once I put the hoses back same thing. If I pull the hose closest to
> the front end of the car, the engine stops rev'ing up and dwn. Another
> thing I did is replacing the all hoses to vacuum adv, I disconnected the
> power plug to the vacuum control module (left portion of firewall) and the
> car stops rev'ing up and down. SUGGESTIONS????