Sounds like a common Evo cut out issue.. which is a malfunctioning cam position sensor. I think your Nimbus has the identical part as an evo. I know the Crank AS code has come up, but that happens on Evos as well when the Cam sensor dies! Pretty easy to swap out compared to the crank sensor.. Got any Evo mates you can borrow one from ?? , before you go to the trouble of the crank sensor .