My jato is 10 years old to me and still has the original RPM arms, bumper, and stock front tower, axle carriers on it. I just ran it yesterday after converting it to electric. Not really noticing anything being rigid or brittle on it. The rear tower breaks a lot, but that's just poor design. My...
Since it's not too tough to do, might be a good idea to tear the engine down and inspect the internals. Could have a fried bearing or your con-rod is dying. The 3.3 is pretty well known for shelling con-rods, but it's usually pretty abrupt and destructive because the rod splits in half.