my service engine soon light on my 92 cutlass ciera came on and I started losing compression what are the possible problems?

What is your question?

engine light came on and it started losing compression on the hills it would only do 20 mph

What makes this problem better or worse?

at speeds of 35 to 45 mph

How long has your 1992 Oldsmobile Cutlass Ciera had this problem?

one week