[GTP Dad]

When this happens does the security light come on? If it does you have a problem with the pass-lock system and need to get it repaired. If the security light does not come on you need to replace the crank position sensor (Hall) sensor. When these go bad they will often cause the problem you indicate and it appears to be a very common problem on GM engines. When the CPS goes bad it may or may not throw a code to the computer.