I have a 93 GMC S-15 with 157,000 miles. Sometime you shut it down and it will not crank. The engine cranks, but will not start. Sometimes it will start after appromxity 2 min. Then others it will not. There are no diagnostic codes. Then the next day the trucks cranks and runs go. When cold the sometimes engine has a hestiation or fills like it is missing during acceleration. Help please.