had one of these for my first car, loved it but it did cost a bit to maintain as i gave it a hard time.would love another one someday.
-rear diff mounts are the most common annoying fault. the bushes wear through, and eventually crack the mount itself. had one of mine come off in 2 pieces.
-the gearbox synchros are rubbish, usually 3rd gear or reverse will show first. its a downward spiral once it starts going as mine went from OK to unchangable over the 2 years i had it. will cost you more than the car to get it fixed properly though so try find one thats not too bad.
-clutchs are either expensive to get someone else to do, or a bit of a mission to do yourself. they are prone to failing if abused as well, the takeup will gradually move to the floor as it wears , so avoid ones with standard clutches that takeup right from the floor. the pedal box also cracks and its a mission to get in and weld it back up.
-turbochargers fail occasionally, they are actually quite small despite the huge housing anyway so its a good excuse to find the later models larger one and fit that. try find one that hasnt been run over 14psi, and if possible that retains the factory turbo VSV which restricts boost when the engine is cold or the air temp is too hot. its a good safety net due to the crappy innefficient intercooler.
-I went through a few wheel bearings and hubs on mine, seems to be a pretty common toyota things for cars of that era. had the front left go a couple of times, unsure if theres a particular reason for that.
-all 3sgte's leak oil somewhere, usually around the cam cover etc. have a good look over the engine for suspect oil leaks etc.
i'm sure theres more but someone else will add extra. they are nice cars to drive, but they are pretty heavy (1450kg) and don't make that much power standard so they aren't the fastest thing around. they are aging now so it hard to find a really tidy one. they are pretty comfortable on long trips though, and we managed to sleep 2 people in mine for a week or so