Steering is one thing you dont want to lose when driving.

I'll second that!

bump steer spacers... gonna have to look into that! my car was lowered by a PO, so i'm gonna see that. got a new VR for the grey car; i'm gonna lift yellow up next week and check her out..

My bet is on the steering coupler shaft where it attaches to the rack, the split splined connector. If the bolt is not tight there the splines could slip and jump.

Although if thats the case the steering wheel will likely get out of position.

My bet would be the rack, the 240 rack had a little plastic type ball in each end, if these wear and they do, can provide some strange responses in feedback. would doubt on ball joints and tie rods as these clunk substantially when severely worn(experience in a 510 and apprentice wages), you as yet haven't mentioned any clunking. Look at going to a 260 rack as according a Zed guru in Brisbane to provide a stronger solution to the problem. You may also find that the rubber bushes in the rack are persished due to oil, rack may be twisting in the mounts and bringing in geometry issues. Do not fear going to a poly-urethane type bushing here as it gives better feel and doesnt deteriorate at anywhere near the same rate. Good luck with it.