I put back in the factory eprom in my '85 GN and I did not disconnect the battery. Now the car idles very low even dies and I get either a rapid flashing check engine light or a steady check engine light. I have checked the codes but doesn't make sense --15 may not be reading the flashing right. I have gone back to the performance chip and installed it with the battery disconnected but I get the same problem. I'm trying to get it smogged only reason I went back to the factory chip. I'm suspecting I have messed up the ECU. Any ideas???