need help with 89 k2500
 

My truck has been hesitating at acceleration from a stop. It doesent do it all the time. Couple weeks ago i was driving to work and it hesitated then backfired and shut off. It wouldnt start so i had it towed. I replaced the fuel pump, fuel filter, egr valve, tps sensor, ignition coil, cap n rotor. All that and it wouldnt start. Then i changed the ignition control module and it fired right up. Truck ran fine for a week or so and now it is starting to hesitate when accelerating from a dead stop again but doesent do it all the time. Any ideas of what the problem may be???