I don't know if this relates to your problem, but I just replaced the lower ball joints in my 145 and it's a totally different driving car. Previously the steering was heavy, and now power steering would be way overkill. I run 165/15 tires, but I wonder if the "sawing at the wheel" could be related to stiff ball joints. The 4 turns lock to lock also accomodates the tightest turing circle in any car I ever drove.

Anyhoo, the ball joint replacement is easy, with one of those large clamp-type ball joint presses, pickle fork, a decent floor jack, a deep bar clamp (for holding the taper together when tightening the locknut, a 5 " clamp can be used ina pinch) and a 7/8" wrench. The presskit was about $40 mail order.