Just a few things, the 99s are known to have a MAF problem.
They cant always handle the turbulance from a cold air intake
and are known to blow. There is a recall on them but I dont
know for certain if the new ones are more durable. I have also
been warned about the clutches, but haven't had any problems
with mine. Factory compression is 10:1 if that helps.
Sounds like he didn't take care of it to me. Scoobys can get
expensive if your waaranty is up and you need work done on it.
If your short on cash I'd look for another one maybe a 2000.