I own a 95 Olds 88 (non LS/LSS) with 77,000 miles / 124,000 KM. Only
problems I've had with mine is some A/C work (compressor and evaporator); a
couple of door lock actuators gave out, and a problem with the engine
computer. Haven't had a problem (yet) with the plastic intake manifold
leaking, but I do keep a close watch on the coolant level.
I really like it on the highway - I get around 29 - 30 MPG on long trips,
and it's a comfortable car. The 3.8L engine is very economical for it's
size and is reliable, other than the intake problem.
One thought - some of the LSS were supercharged 3.8L, and I don't believe
they had the problem with the intake like the standard 3.8L engine.
Granted, your gas mileage will be less with the supercharged engine, unless
you are very gentle with your right foot.
Hope this helps.