dagwood15t

let a friend drive my car for the day and when i got home he said it was almost out of gas so he put regular unleaded in it 91 octain i always run 98 or higher and ran it for about 35 mins he said when it started to sound funny and wouldn't ideal any more.
so i hooked up my code reader and it gives me 2 codes p0048 and c0100
it is realy hard to start also
any help would be great because im a us soldier in german and the mazda dealers here won't look at my car becuase it has a greddy turbo system on it.
thanks