Figured I better throw my two bob's worth in this discussion.
 
If you added the RCA's to the front and rear, without a alignment it will toe out in the rear making it loose handling. The RCA's also alter the throw of the rear of the car so the wheel moves towards the front then rear over the stroke of suspension travel. This too effects to toe settings on the car. This is a issue with the RCA's as you can change RCA's, then the setting of the toe adjustment pivot point(it requires a lot more than you realise to get zero bump steer), but also the pivot point of the trailing arm at the chassis needds to be reset bring everything back into alignment. No one does this as its a serious task to undertake.
The only way to try and get some consistancy within the suspension stroke is to adjust the "caster" of the rear suspension to reduce the front to back movement within your suspension travel operating range.
Examples:
Mine had a issue with the rear of the car moving around which was caused by the rear toe adjustment link was broken(WTAC 2010). Also had a issue with wheel spacers which rendered the car undriveable on its first outing. Once removed, its was OK. It was also nervous under power, so I raised the car by 10mm each session which settled the car as the 'roll centres' were raised to a manageable level. Also had issues with extreme understeer at Winton last year which was caused by too much bump steer up front. A softer setting in the rear of the car with the shocks will help settle the car too.
 
If you not keen on going solo with this, you need to see someone who is very fussy, has self respect, understands MR2's, Lotus and/or Porsche to find the problem and fix it.

Thanks Steve.
ill have to remove the RCAs first and see what the car does then go from there.

Glad to help out where I can.

I had similar issues.
 
The first time it was my front ball joints (front swinging around during corners), got them replaced and all was well.
Second time the rear started to swing (same issue as you've described) so I got the rear ball joints replaced, it helped but was not perfect.
The original suspension was tired anyhow after 20 years, so I swapped in coilovers (yaay).
Now it feels much better! pretty sure the rear left strut was rooted.
It's still doing a slight ... dance? shall we say... strangely in a straight line, but I think this is down to not getting an alignment as yet after coilovers (just put them in this weekend past).
 
Check those ball joints!, takes two people though and a hoist, one person swings on the wheel and the other watches for ball joint play.
 
Hope that helps!
 

ball joints have come up in my search a few times now so looks like i will get them checked as well
thanks guys..
 
cheers

Steve.
If you haven't done it already, also check out the REAR track rod ends, especially the outer one.
They are press- in sealed rose joints.
Any play in those at all will make the car handle like shiiiiit
 
 

Thankyou,
I changed from the original rose joints to a link which is 30+mm lower than standard when I did the mods to the roll centre/ RAC's etc. It was handling OK when I ran at EC last year.Welding up one of the broken tabs may have helped.. Was good at Winton, no issues with movement at the rear, just bump steer issues causing way to much understeer in the slow corners.

I think he meant Purple Steve, not B24 Steve.

Take it to a suspension. Specialist I would recommend

kameleon

I think he meant Purple Steve, not B24 Steve.

Thanks kam.
Yes, I did mean Purple Steve.  Sorry for any confusion.
When I first got my car, one of the rear track outer rod rose joints was shot, making the car very unstable.