Yes 92 was the worst year for the 3.8 lifewise. Most only make it to 250 ,000 miles if taken care of.
Engine will be alright, I would worry about the transmission.
Lets see.
DO NOT USE BOSCH O2 OR PLUGS. bosch + 3.8L = bad news.
Replace plugs with AC Delco standards
Replace 02 sensor with AC Delco only not bosch, trust me on that one.
If it is lacking power I would look into checking out the cat.
is it showing any codes?