1994 Chevy Silverado Engine - Spark loss at plugs and coil

I can see blue spark loss at the plugs and at the coil of my 5.7 engine runs poorly and misses. First attempt to solve this problem - I replaced coil, distributor, rotor, distrib. Cap, spark plugs, and wires with Genuine AC parts from the dealer. Problem went away for 1 day and then problem returned. I can again see blue sparks when viewed in the dark under the hood at each plug and at the coil - runs poorly and misses.