here is a little backgroung on my car first...i have a 383 in my 67 camaro with a gen7 setup with an lm1 wideband hooked through the dfi..the intake is a holley stealtram....now for the problem...i really haven't driven the car much latley(for about a month)...anyway today i took it for a ride and it started to backfire like it was lean...when i got it home i hooked up the laptop to it and sure enough its real lean all of a sudden...the lm1 and the gen7 software are in sync as far as the what the AF ratio is...is it possible the fuel pressure regulator is or is going bad??if so what can i do to test it???any other ideas are more than welcome....any help would be appreciated....
mike

 

Use a fuel pressue gauge to determine what is going on.

 

What is real lean? After sitting....I d guess a vacuum leak? That would cause false map sensor reading. What is the map sensor doing? Is it lean all the time?