My tame mechanic advised me to change both cam & crank sensors as part of tracking down a stubborn glitch.
It didn't fix the problem but,
I was surprised at the improvement made by each sensor in terms of general smooth progressive response.
The van had become a bit rough around the edges, now it drives almost like a new one. Well worth the 10 quid each.
If I could only find the cause of the feking glitch.