2 pumps same symptoms. It ain't the pump. Have you looked at what the voltage at the pump is? Possibly there is to much electrical resistance somewhere along the wires and connectors. Clean the connectors and use dielectric grease on em. I've started to see electrical corrosion problems on my '89 mini truck.

The thing I'd check is the mass airflow meter. I have an '89 with corrosion in the body of the MAF. The air measuring flapper likes to stick and was originally giving symptoms similar to what you mention. I need to pull it again and do something to keep the corrosion away.