Working on a 1988 c1500 chevy pickup with a 5.7 liter engine . Engine will not start untill you spray carb cleaner into throttle body , after you spray the engine will start and will run fine untill you turn engine off. No injector pulse at crankover untill it has been sprayed. Have already replaced distributor with new distributor still Have same problem .tried another computer on vehicle and still had same problem. The two grounds that supply injector pulse from the ecm are present untill you go into crank position. Throttle position sensor is reading correctly. Any help would be greatly appreciated.