Update: After a few weeks of fighting with the cluster floating in the car (unbolted and dash surround apart), so when an "episode" happened i could move it around to make it normal again... i finally did some further disgnostics... ie. poking and proding... it appears the connector was very loose (probably throwing off some of the pins), so i wedged some cut off zip ties in there as shims and it appears to work fine now! 2 weeks of driving around ok. i guess that was the problem! just a loose connection! hopefully.