Steering wheel jerks 30-40 MPH

What you're describing is commonly caused by a loose rack and pinion steering gear. Yours uses two bolts on the driver's side, so rather than just one to come loose, I'd more likely expect to see the rubber bushings have deteriorated, allowing the steering gear to slide back and forth. There's a rubber sleeve on the other end, so that doesn't hold the gear from sliding. Worn control arm bushings will cause this type of darting from side to side, but they show up continually while driving. Steering gears tend to remain a little tighter, so it takes some effort to cause them to shift position, then they tend to stay put longer.

The way to identify this is to have a helper turn the steering wheel back and forth about a quarter turn each way while you watch the steering gear. Being mounted on rubber bushings, it might move a perceptible amount, but if those bushings are worn, you'll see the gear sliding back and forth perhaps as much as a quarter inch.

I don't see the bushings listed in my usual sources, but there are other alternatives. First, check at the dealer's parts department. For all brands of cars, you'll typically only find the accordion boots available through the dealer. Inner tie rod ends were not, but they were available from the auto parts stores. Sometimes you'll find rack and pinion rebuild kits, but that isn't common. Special tools are needed. There's liability concerns if something is done incorrectly, and professionally-rebuilt gears cost very little today compared to 20 years ago.

With that in mind, the mounting bushings aren't part of the critical internal system, so they may be available without buying a whole new steering gear. If you can't find replacements anywhere, the next solution is to harvest a pair from a salvage yard. You can find them in a pull-your-own-parts yard, or ask to get them from a "core" assembly. Salvage yards collect these types of assemblies and sell them to the rebuilder companies. There's no way a rebuilder is going to sell a rebuilt gear with old bushings. Since they're going to be replaced, the core doesn't lose its value if the old ones are removed.