96 regal gs 3.8

Hello-

Yesterday I got a code p0108 - Map sensor trouble code.
I checked the pvc valve it needed replaced. thought maybe that could be the problem. didn't work. So i went ahead and replaced the map sensor. Again, didn't work "service engine soon" light came back on again. any ideas??? the car runs fine. haven't noticed a drop in fuel economy.

My 96 Regal Custom 3.8 has had the light come on maybe four times. It always goes away after 2 days. It runs fine. I don't have a way to check for a code. I am not going to worry about it, except:
Notice my string about it quiting on me. The dealership said it ran fine for them and left no code.