OK, I no longer think it's the vac temp switch, cuz if it was that, it would do it when you were sitting still, at idle.

I'm thinking more about the VSS (Vehicle Speed Sensor) at this point, but don't really have an answer for ya. Lemmee consult my sources (who are out of town...)

C/YA!
Jeff
'88 Trooper
2DR LWB 4ZE1 5SP
bone stock DD