How to solve a code 35 in a 1993 GMC 1500 with a 4.3 engine?

Before going any further verify that none of the spark plug wires are old or damaged or located near the wire to the knock sensor. Wrapping them in aluminum foil can also eliminate this problem. If this doesn't help, follow normal diagnostic procedure.

according to my information a code 35 on 1993 gmc is an idle air control system problem/idle speed actuator.