So for the heck of it I decided to switch out my Map sensor in my 3800 SC Monte Carlo. The sensor I used was a practically brand new one i took off of my 01 regal non supercharged same part number however the car would not start. I put the old one back on and it started up. The actual reason for doing this is the fact my car is burning rich I'm only getting 20mpg hwy. I have replaced o2 sensors, deleted resonator, put a KN CAI on, clean throttle body thoroughly. Put NGK iridium plugs #5599 and new wires. Had the injectors checked and they are fine also my oil smells like gas....any ideas? I appreciate your time

 

I believe the map sensor is different, one reads boost and one don't but don't hold me to that.

I would be checking the maf, fpr, etc also