96 K3500 chevy, 454 has an intermittent hard starting problem. Usually the truck starts on the first crank. Every several days or couple of weeks it takes 5 to 7, 10 sec. cranks before starting. Between cranks, the engine diesels but has not yet started. Then it starts. No problem starting the rest of the day or several days after. No codes show on scanner. The truck runs fine with normal performance. Replaced crankshaft sensor, fuel regulator, fuel filter. Fuel pressure is a steady 55. I haven't found anyone who has heard of dieseling while cranking. What is the problem? Intermittent problems are so hard to solve.