2000 GMC Sierra ECM 2 fuse

Your ECM or Electronic Controle Module is vital for your vehicle's engine to receive spark. I suggest checking the grounds on the ECM. If these are good, run a test light across the fuse terminals and wiggle the wires in that circut. Iit lightsup bright that means youave a chaffed wire thats groundin intermintantly.
Also check for voltage at plug wires. If one is lower than it should be, suspect faulty ignition coil.