Fuel filter light. I have had this truck many years and did not know it even existed. Having some trouble with the cold weather, barely made it to work. Surging, bucking, stalling. This light is located on my 89, in the very lower right corner of the cluster. On the way home it was still throwing fits but not as bad. I could ease up on the throttle cruising, and the light would go out. But when putting a load on the engine, the light would come on again. I finally made it home and put 1/2 a bottle of 911 in it. Hopefully that will take care of it.