hook up a scanner to it first, same thing happened to me n a shop told me i needed a pcm a shop told me i needed a tps, after doing some digging i found my real problem was just a mis adjusted ckp, although the tach in my truck worked for a split second the signal changed in the pcms eyes it didnt, you could spend a lot of money swapping parts and pcms when you really dont need to, a correct diagnosis will make it a lot cheaper, not saying its not the pcm but its more unlikely for it to be that, other things that make lock up, od and cruise not to work are things like vss, temp sensors and other missalianious sensors, check to make sure your pcm is getting the correct readings before you replace it.
