Spent a lot of time working on the first generation probe GT's with the 2.2 intercooled turbo.
First off? If it has a 'fram' filter? Rip that sucker off and replace it with a napa gold series (made by WIX) and that will shut up most (if not all) of the noise from the HLA's the valve train uses.
Brake wise, not to bad to work with. Drive train? Weak link is the pin in the diff. Doesn't matter if it's a standard or auto. Nail it to hard, and the pin will shear off in time. Very common fail point. Engines are built fairly strong, but opinions vary--ours ran strong, but they are prone to snapping exhaust studs out of the cylinder heads. The turbo units? Use both oil and coolant, so make sure it's kept maintained. Always let the engine sit for about 20 seconds before shutting it down. (on the off chance the turbo is still spinning---that will give 20 seconds for it to finish winding down)
Now the bad part. If you live in an area that gets snow and road salt? Take it to a shop and have them put it on a lift. Key points you want to completely INSPECT!!
Fuel tank: ours rusted out, needed to be replaced.
All lines, including fuel: All our brake lines rusted out.
Unibody frame: THIS IS PARAMOUNT!! Inspect this completely!! Mounts where the rear track bars attach should be rock solid. Front unibody section from the under the seats---all the way forward...complete inspection!! Key fail point--Just where the unibody wraps up at the firewall. (look under, you'll see and feel the unibody where it comes forward and slopes upwards at the firewall behind the front tires.) This is where ours failed. Put it up onto a jack stand--and the stand went through the frame. It rots from the inside out.
Last major fail point. Both front struts use a rubber band glued to the strut housing mating the strut bearing plate. (best way to describe it) These will FAIL!! it's just a matter of time. You will know when it happens, as the steering gets all shades of hard, and a matching grinding sound when you turn the wheel. (the upper spring plate will crush into the bottom of the strut housing---napa sells the plates, and they are reasonable cost--just need a shop bribed with donuts to lend the use of a spring compressor--the hand ones will not work---been there, done that with both sides)
Power steering issues: This car uses VSS. When it works? It kicks butt!! Ensures just enough resistance on the steering for cornering. The bad part? It's a fused system that is linked with your turn signals?!?!?. (found that one out the hard way)
Power steering cooler: It's hidden inside the right front fender. About 6' long, wrapped in a unique shape. All you'll see is two connectors at the fender. They rot out, and you'll have a power steering leak you'll wonder where in the heck it's coming from. Easy fix, we built our own.
In a nut shell: Provided it's very well maintained, normal servicing, and the body is as near to mint as possible? Very decent ride---and when that turbo kicks in? Trust me--it's wicked quick!! (we put a cone filter-racing style on ours---made it even faster).
If the underbody has signs of rust---or new paint (some owners will spray paint the underside to hide these problems) I'd walk away, unless a shop can verify the unibody frame.
Ours died due to the frame rails where it goes to the firewall, and slightly upwards. My wife crushed the other side with her hand, it was that far gone---and outward looks? It looked totally normal!
Probably more info then you wanted, but I've a lottttttttttt of time spent working on our 89 probe GT. Fast as it gets---died before its time due to road salt.
S-