Got PCM Back
 

So I got my PCM back yesterday and I must say wow! I can really tell the difference. But it does have one problem and I don't know what it is. If you all could please help me out with it.

The car runs good, but after it has warmed up and youre driving down the road at regular speed and let off the gas to coast it will go from whatever RPM your running to about 1000 rpm and then back up repeated. As long as you give it a little gas it doesn't do it. Does anyone know what this could be? Not sure if it's the PCM or something else.

Possible vaccum leak?

It could even be your maf sensor. I know my car has done that when I had it unplug for a bit.

After running the codes and getting the code po1000, I found out that I have not driven the car enough for the PCM to calibrate or something to that extent.lol Not real good with the PCM, but I have learned a lot about them in the past week.:)

Does a case learn need to be done?

Was the code P01000 or P1000? There is a big difference as to the cause. Your description sounds more like the P1000. You get that code when the PCM is unable to complete the scan test (not alll. Wiring is the usual culprit to a sensor or fuel injector.

If the code is P1000 it could be that you just need to perform a GM drive cycle to get all the monitors into the ready state.