Hi Simon.

Thanks for your reply.

You're not the first person to suggest cam/crank sensors. To be honest I fitted a new crank sensor as a bit of a leap of faith as they're not a fotune to buy. Sadly it didn't cure the fault!

I have just replaced a 4.7 V8 Cherokee engine so I've got a couple of cam sensors I can try. I will post the results.

I put some posts on a couple of the US Jeep forums and it was a Jeep tech from Upstate New York who answered! Handy contact!!

Regards - Paul.