Shaking

Experience strongly disagrees with you, Ed, assuming it's the "shaking" that's the issue, not actual inability to gain speed. 65-70mph is the wheel resonance point for most wheel setups, so I'd look for a bent wheel (even a triangle can balance!), bad tire bead, or even grease-starved DOJ before anything else. Try rotating the tire-wheels and noticing if the shake now moves from steering wheel (front) or seat vibration (rear). That will determine if it's a wheel or tire, then check that pair carefully, rebalancing while LOOKING at the spinning wheel for out-of-roundness. Squeeze the OJs to help massage grease back into the joint to cover the possibility that one spun dry over the decade. Report back after investigating. I'm guessing that the shop that rebalanced the tires also rotated them into new positions that now make rotational imperfection obvious. This is most often noticed when an out of round REAR wheel/tire is moved to the front, where the steering and brake pedal are more affected, and thus noticeable to the driver. Ern TS/G