[ICETOO]

Greg, what sort of ECU (or PCM if you prefer are you using).

It is a fair bet that the ECU has hard reset and is now back in learning mode...I am assuming that you have something like the DASH DAQ set up as well. Does this also have any after-market tune maps as well that you load in via the OBD II port. If so, reload the stock ttune then over write with the performance tune.

The ECU will take some time to get the AFR (stoichiometric ratio) right again to run at optimum performance.

Also check that your O2 sensors have not fouled up but the diagnostic on the dashdaq type kit would register a MIL error if significant.

When ever I disconnect my battery on my LS1, or even the XR4 I have the same issue.

This will normally sort itself within 100 kays or so.

Best of luck mate!