"open loop" problem with 2000 SL1

on friday I encounted a problem with my saturn that seems to have
mushroomed to something bigger. I was accelerating up a hill and when
the car hit 40 it began shuddering like it was out of gas even though
it wasn't. I noticed it didn't do this while coasting. I dropped it
off at a garage that was recommended to me by a lot of people and
found out from them today the computer in the car is complaining about
5 or 6 diagnostic codes ranging from low coolant which obviously isn't
true because the fluid is fine, and the fuel mix being off. Also
apperently the "body control computer" isn't functioning properly and
isn't talking to the "ECM" and is causing the car to run in an open
loop. They asked if the check engine light ever came on which it
hasn't or any other lights stop working or start working. THe only
thing I've noticed in the last 8 months or so is that the little green
light for the daytime running lights stopped working which I ignored
because it bugged me anyways. My Saturn has about 59k miles on it and
this is the first problem I've had with it. Anyone else have any
similar problems or know if this is common?

Thanks,

-paul