I have a 2001 s40 that I have been driving for the last two years with minimal problems. Recently I got a check engine light and noticed the car was not running that well - idle at really low RPM, poor pick up. I took it to the mechanic, he read a p0172 and decided to change the engine thermostat. I drove the car for about ten miles and the check engine light returned, this time it read a p0101. The mechanic told me I could continue to drive it for a couple days before bringing it back to him. As I drove the car the check engine light would go away for a bit and then come back, this cycle continued a couple times. After having the mechanic take a look at it again he said he needed to clean the MAF and everything should be fine. I drove it out of the mechanics shop and the acceleration was much better. Five miles down the road I got the check engine light again and the code reading p0163. I drove it for a couple days during which I was getting poor gas mileage, rough idling, car stalled a couple times, and acceleration was still not "normal". This time he changed the MAP sensor. I drove the car around for a about 50 miles and then started to notice an occasional rough idle, and it stalled once - but no check engine light until a few miles after these symptoms kicked in. Anyone have any clue what may be going on here or what needs to be changed or looked at? I have a smog check for renewal coming up so I need to figure out what is going on here. I am debating taking it to the dealer and biting the bullet, but I wanted to see what your thoughts were.
I greatly appreciate any help/advice you guys might have.