98 gmc random miss fire

[Jessi Theisen]

I have a 98 gmc 5.7l vortec z71 it has a random miss fire. Ive changed the following....spider injectors, fuel pump and fuel filter, plugs and wires, changed the distributor cap and rotor, oil pressure sensor, changed TPS, put in a new ground wires, changed the air idle module, cleaned MAF. Truck runs great for 30 seconds and then starts out with one miss, then two and so on. Then smooth's out for 2 sec and then starts randomly missing again. What could it be?

[dsmmace]

Replace the distributor as the gear is likely worn, make sure it's timed correctly as per the service manual with a tech 2.