1994 Chevy S-10 SURGING

I'm taking a guess that this has TBI on it. If it does the gasket beneath the TBI unit is probably leaking. Get some choke cleaner and spray around the bottom of it while running. If the idle picks up then you've found the problem. Also make sure that your hoses are in good shape as they tend to get soft, especially the one going to the MAP sensor on the firewall. It pinches off or sucks together and the MAP won't allow the truck to run right, but the gasket has been a known problem as well and the computer is trying to richen the mixture of fuel/air to keep it running correctly.