1991 Chevy S-10 No Throttle Response

I was driving along and the engine sputtered and then it had no throttle response. Pumping the throttle kept it going but the engine would quit at stop signs. Restarting worked however feathering the gas petal would only get the truck up to 25 - 30 mph. Have checked vac lines, plugs, wiring, dist cap, all to no avail.